It all depends on a lot of things ... like where your foreskin has been ... how clean you keep yourself ... etc.
Not to scare you particularly, but that sounds like it could be a virus as in herpes; your brief description sounds very much like some I've seen. It could also be just abrasion from clothes. Or it could be bacterial from being hot, sweaty and maybe not getting as clean as it could in the shower. It could be another STD too. But almost all skin level infections are red, sore, and irritable, so ...
Bottom line, you do want to get it checked out; by a doctor, soon. Your doctor, the county health clinic, a walk-in clinic, wherever. Just don't delay having an expert view it.
It has been nowhere it shouldn't have been for the last 15 years, the length of time I have been married. I have been doing a little research myself and it looks I might have symptoms of phimosis. Could this be a contributory factor as when my penis is erect more pressure is being put on the foreskin. If so, is there anything I can do without surgery to ease this condition?
Thanks for your help so far,
BTW, you don't have to have it be "nowhere it shouldn't have been". Example: some fantastically high percentage (like 90%?) of us have the cold sore herpes, easily transferred from lip to tip, eh? Let me count the ways ... as Shakespeare would say. And there are others. All infections don't come from being "naughty".
Definitely several options, your suggestion may even be the correct one. But any further comment by me is me is but speculation that delays what you really need. A doctor's gloved hand and practiced eye, backed by training and experience, needs to be your next stop.