Really? That's sad. I suppose in some small way it must be true, ongoing physical problems are hard for people to deal with. So, as much as I hate to admit it, in the grand scheme of things it probably costs you more friends than it gains you, between their feeling weird and your (general your, not your your) inability to participate in certain events. But, still, it sucks and I hope it's not very common. The friends that are still by your side are ones you know you can really count on, at least. :)