Red irritation for 5 months now, can't heal it, I need help

Hello everyone!

I hope some of you can give me some tips, cause I really don't know what to try anymore... It's 5 months now that I have a red irritation on the right side of my penis gland. It doesn't seem to be an infection, no blood, no substances loss, but I often hav this burning sensation, especially after sex/masturbation.

Here's a picture if you wanna check it (explicit, don't look if you can't stand it):

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So far I took urinal, uretral and sperm tests, all with negative results. I applied different creams all based on cortison, no effect at all.

A dermatologist told me it's not a big deal, no infection, just an irritation. Yeah, alright, but how can I fix it?? It's becoming really annoying, please help :(

I was thinking about some kind of light balanitis but I can't be sure... any ideas? Any input is veeeery much appreciated, thank you guys!