ouch, my man parts are broken!?

help me, I got a problem that is recurring I have a split just under my glans and every time I have sex, which hasn't been that often, it rips open. Had sex last night and it was so painful I had to stop!

I seem to get a swelling around the glans, where the circumcision scar is, between the glans and the shaft, and it splits too. It kind of blisters up. don't see it as being any 'manual, or digital friction issues' cos I'm near 50 and don't do that, so often. Don't think I got herpes or anything, gotta go see my doc asap, but can't do that today!

I'm a big guy, but thats never been a problem before!

youch! Any quick suggestions? I'm a bit confounded, need to think back to when this started, see if I can figure out sumthing to help the doctor?