As someone who's currently struggling with a health issue, let me give you a piece of advice:
The reason we (chronically sick people) don't usually tell people what's going on isn't because we don't want anybody to know (in fact, it's really nice to talk about it and tell people). We chose not to bring it up because most people don't know how to react. They usually say, "that sucks," "I'm sorry," or "what can I do to help?"
We don't need you to tell me that "it sucks," because believe me, WE ALREADY KNOW! And everyone is always "sorry" but that doesn't make the situation any better. Rather, listen to and VALIDATE our feelings. Tell us "that sounds like a rough situation," or "that's a hard thing you have to go through." Ask us about it more, let us help you understand rather than you giving us your prejudged sympathy. Ask us specific questions rather than the generic "what can I do." There GENERALLY isn't anything you "can do."
Ask how you can help them in certain situations or ask them if there is anything you SHOULDN'T do around them (for instance if someone has chronic pain or fatigue maybe suggest an activity that isn't very active). Be willing just to listen to them talk or vent without interrupting with something you think is relevant when you really don't know what it's like. Your validation, kindness, and friendliness is often enough to bridge the gap of isolation and struggle we feel.
And DON'T START ACTING WEIRD AROUND THEM. Just because you know more about them doesn't mean they are any different than they were before you knew.
