You have been gone for 5 months, there should be some nervousness about going back, right? Recognize that...it isn't the same as a two week vacation (don't you wish!). Cut you some slack. I might prepare 1-2 'canned' responses to "how are you" or "what was wrong". People probably DO care, but, don't want to tread on toes, and, really, some people are so busy/caught up in their own lives they might not really have noticed.

Some people will take their cues from you, so, I would try to come up with a couple of things that sound natural, and slightly off-putting as to more questions, and maybe always respond with, "you know, I am glad to be back! Now isn't that just crazy?" That sounds like a question, and can allow the conversation to drift from you to them, and what sort of stuff has been going on.

Good luck.