I'm sorry to hear of your disposition.
I don't know the nature of yur injuries, nor am i a doc type.
Swimming is usually pretty damage free and after a good hard swim you;ll feel good and once the endorphins kick in, you'll feel great. Over and above that, it'll keep you lose and fit.
ANY sport that will not hurt you, make you sweat and get those great endorphins pumping through your veins will keep you good at least for a few hours of the day, if not all day.
Hope you feel good
Hoepoe