Thank you for your response.
I've done some reading on post-inflammatory hyperpigmentation and it certainly seems to be what I'm suffering from.
One thing I have noticed is that this area is very prone to variation in color. For instance, if I wake up in the morning after having had a lot of nocturnal erections, it will be a much more intense red color. It also gets darker after exercise, when I am hot, or after masturbation. This makes it difficult to gauge progress of recovery, as it can stay inflamed for days afterward at times. I've tried abstaining from masturbation, which does seem to help, but that eventually leads to more nocturnal erections, so I end up no better off.
Is this phenomenon normal for PIH?
It looks like post inflammatory hyperpigmentation. Post-inflammatory hyperpigmentation is a condition where there is an excess amount of pigment following a disease process that affects the skin. Without treatment, this usually takes about 6 months to resolve and for the skin color to go back to its normal color. Topical treatments with acids and chemical peels can be effective but can take a while for the skin to totally revert to its normal color. Microdermabrasion can also be done, but this might require several sessions. Skin resurfacing using lasers is also an option.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.