So sorry to hear about your health woes
I don't know if it helps any, but I have sometimes gotten myself really worked up because I had this "if he does this, it means he loves me, if he doesn't it means he doesn't" idea. I mean, could it just be that your bf is stepping back because he thinks that's what's required of him?
I have always been the kind of person that wants lots of affection and attention when I'm sick/down, but my bf and a few other people who are close to me are really bugged by it and want a sort of respectful distance when they're having issues.
Maybe just let him know that even if you're getting care from someone else it's still important for you to get his support too, if you haven't already of course...
Being sick has a way of making shit harder