Upvote:3
I have used travel health insurance from CareMed who, like World Nomads, provides post-departure policies if your departure date was less than three months ago. Having experienced both CareMed and World Nomads (and have submitted claims to both) I can not recommend World Nomads since they revealed some hidden restrictions and blocked my claim, while I had a positive experience using CareMed.
(And not related, but I would like to recommend GeoBlue for travel health insurance if you are a US citizen and can purchase it before you depart on your trip. They are awesome.)