People get sick and die next to me - my karma?

Sorry to hear that... I hope you've got pass of it now.

It seems you may be under temporary emotional stress that prompt you at this immediate moment think in this way. Experience is experience, Karma is Karma, when you equate and sum up as "my Karma to experience" it doesn't help to see things in the objective perspective. Care and lost of the cared is the element for Samsaric journey when the 12 Nidana(s) fementated and play out the drama we called world & life.

However, people associated the closer meant they shared stronger the Karmic deposits, they likely were interacting more vigorously with each other in the past so stronger hate/love forces were accumulated, comparatively. The way for the drama to play out the Karmic force could be very unexpected. On the other hand, kinships share DNA that is the expression of Karma (my insight, genome is the expression of Karma). In this sense, members within the kinship could share similar heath coditions. Last, people do have "energy" vibrations that may be good or bad to the recipients, fortune telling is not completely superstitions just because these fortune-tellers don't earn the PhD of Chemistry or Biology they don't use the accredited jargons the scientists used. So some people may affect others. In the Sutras there were many accounts describing how people were gladden and rejoicing merely hearing few words or simple blessing from the Buddha - his "energy" field can be seen by nake eyes as the glow emitting from him.

Having loved ones or pleasurable company is Vipaka(results) of good Karma. The departing of loved ones or withering away of pleasant experiences come under the first noble truth. You getting sad about it is the Vipaka(result) of bad mental Karma of clinging to loved ones or pleasant experiences.

Karma is only understood by the Buddha fully since it is a very complex topic. But having said this the Karma you do generally affects oneself, but there are instances when this is not the case (E.g. Tsunami during period of King Kelanitissa affected the whole country though it was the King who committed the karma). But again for Karma to take effect the environment needs to fall in place. Say you have a Karma to part with loved ones. Then it might affect people around you but cannot be definite on this.

Also there might be other Niyama Dhamma which might have effects. It could be pure randomness or coincidence. Not everything happen with Karma

Also following might be helpful to understand Karma more:

• Karma by Piya Tan
• Group Karma? by Piya Tan
• Maha Kamma,vibhaṅga Sutta
• Cūla Kamma Vibhaṅga Sutta
• The Workings of Kamma by Pa-Auk Tawya Sayadaw
• pañcavidha niyama - Wikipedia, wisdomlib
• THE NIYAMA-DIPANI: The Manual of Cosmic Order by Mahathera Ledi Sayadaw

Your grandfather in the hospital is not because of bad karma. It is because of the aging & decaying of the physical body. The Blessed One declared:

All that is dear & beloved there must be change, separation & severance. Of that which is born, come into being, compounded & subject to decay, how can one say: 'May it not come to dissolution!'

Mindful and clearly comprehending, reflect in this way: 'Impermanent are all compounded things. How could this be otherwise?'

Maha-parinibbana Sutta: Last Days of the Buddha

Buddhism states, even when there is death, the good karma a person has done will bring good results & the bad karma person has done will bring bad results. Therefore, when your grandfather is in hospital, you should think about the good karma your grandfather did in his life. To quote:

These beings — who were endowed with bad conduct of body, speech & mind, who reviled noble ones, held wrong views and undertook actions under the influence of wrong views — with the break-up of the body, after death, have re-appeared in the plane of deprivation, the bad destination, the lower realms, in hell.

But these beings — who were endowed with good conduct of body, speech & mind, who did not revile noble ones, who held right views and undertook actions under the influence of right views — with the break-up of the body, after death, have re-appeared in the good destinations, in the heavenly world.

Bhaya-bherava Sutta: Fear & Terror

If your grandfather dies, you must think about his good karma and you must make merits & dedications for him. The scriptures state:

In five ways, a child should minister to his parents:

(i) Having supported me I shall support them,

(ii) I shall do their duties,

(iii) I shall keep the family tradition,

(iv) I shall make myself worthy of my inheritance,

(v) furthermore I shall make offerings in honor of my departed relatives.

Sigalovada Sutta: The Layperson's Code of Discipline

In conclusion, the only bad karma that is occurring is your not having right view in the mind about the Dhamma. Even if your grandfather in hospital causes you grief & sadness, as a Buddhist, you must also have Dhamma in your mind, as the Buddha taught, as follows:

There are these five facts that one should reflect on often, whether one is a woman or a man, lay or ordained. Which five?

1. 'All are subject to aging. Have I gone beyond [am I peace with] aging?

2. 'All are subject to illness. Have I gone beyond illness?'

3. 'All are subject to death. Have I gone beyond death?'

4. I will eventually be separated from all that is dear and appealing to me.'

5. 'I am the owner of my actions, heir to my actions, born of my actions, related through my actions and have my actions as my arbitrator. Whatever I do, for good or for ill, to that I will be the heir.'

Upajjhatthana Sutta: Subjects for Contemplation

Click here for Alternate translation.