Thanks for the query,
You might have developed a bacterial infection initially,
It has come down with the use of peroxide,
but following that you might have developed post inflammatory pigmentation
You can use a mild oral steroid
paste like triamcinolone
This will give you relief.
Please meet a dermatologist
for exact diagnosis.
Let me know if you have any other doubt.
you can ask a direct question to me on this forum, following the below link.
Wishing you a good health.