I'm so glad to hear the problem is not as bad as it could have been, Jennifer. I hope the docs are able to narrow down the source of your difficulty and find a workable solution.
I read your previous post with tenderness, and wondered whether there I had anything to offer. Having pondered the situation, I can really understand your friends "going missing." I have had the same experience myself, and have given it much thought. And, when I have had friends struggling with serious health issues, I sometimes find myself stymied about what to say. I've been around a lot of years, and observed many crises with friends and acquaintances.
When a friend or relative is in crisis, I notice that I'm immediately thrown into uncertainty. If I say too much, I have been accused of "prying" or trying to "offer unsolicited advice," or being "trite" or "unsympathetic." There are so many ways to say the wrong thing, which might have actually been the right thing if said to somebody else. And of course, if I stay silent while I sort through my own reactions and wonder what might be the right thing to say, then I may be considered "uncaring."
And there's also the helplessness and fear that many people feel in the face of catastrophe. We're probably all intensely curious about other people's crises, because it's so easy to imagine ourselves in that position, and realize, at least for a moment, how fragile and temporary all our lives are. (I think this is one reason traffic slows down on the 'other' side of the highway when there's been an accident – people look and wonder.)
We live in a culture of personal freedom and self-reliance, and every possible guarantee of a long, safe life is part of our national fairy-tale. As a result, weakness is almost culturally disallowed, or even seen as our fault. Still, we want to watch it from a distance, because it's nearly overwhelming to face our genuine lack of security and all the questions it raises. (OMG, I couldn't deal with it if that happened to me/my spouse/my child! OMG, would all those expenses be covered by my insurance? OMG, what if this friend needs to lean on me in ways I'm not prepared to offer – time; practical help; emotional support; financial assistance?)
So, in the face of all that uncertainty, people back away. Some quickly get busy with their own families and projects so they don't have to think about or face their own vulnerabilities. It's sad, and it's hard, to be the one so quickly abandoned. But it's also a time to take the measure of one's friendships. People who do sincerely care about and feel connected to you will still be there. They may not know what to say or do, but they will still be there. It's just not realistic to expect less connected, less energetic, or less "ripened" friends to step forward.
I wish you the very best.