I think zeeb's advice is solid. You could have some sort of allergy or intolerance that is giving you problems. Assuming you have gotten rid of the obvious like smoking try cutting out things like dairy or glutens and see if that does any good. I do sympathize with injury making it harder to stay in shape. I tore up shoulder last summer and a lot of the things I used to do to stay active hurt so much I avoid them. No sage advice except to say that staying active has to a priority.