I have the same condition and its been 4 weeks since I had unprotected sex.
I dont have the tests results now, but... I'm pretty sure its some issue related to irritation or something.
I also have a red and a bit swollen frenulum. SAME thing, but then I also have Very very small lumps that the doctor said that they were unnoticable so I have no idea...
I've been reading and it can be caused by the fact that I move a lot (I'm uncircumcised) or that I have not been careful at some point. I did use soap on it... I think anxiety may be a cause, too................. I'll keep seeking for answers, but I'm not too sure if there is something to worry about. its been about 5 days since...