Penis trouble: foreskin red and swollen. Discharge. Head fine.

First of all - the head itself is fine so I know it cannot be balanitis.

The foreskin is swollen and red. It is sore to touch and hurts a bit to pull back but it isn't tight.

The whole area is quite wet - there is lots of discharge. At first I thought it was just pre-cum but it doesn't smell very nice and at times there are globs of it which are creamier and thicker than precum is.

This has happened once before - during mid-December in fact.

After about 4 days it went back to normal but with very tight foreskin. After a few days the foreskin was back to normal.

I wash regularly.

I have sex a couple of times a week but nothing too vigorous. It can't be an STI as my girlfriend and I have been going out for four months. I haven't had sex with anyone else ever and she is clean - or at least neither she nor any of her past boyfriends have ever had any problems. I also doubt an STI would have hung around 6 months and then suddenly given me a little issue, gone away again, then come back.

I am seeing a doctor tomorrow afternoon but would appreciate the thoughts of people on here anyway just in case it gets better by then.