If it's not flat or raised and just discolored, then it's probably hyperpigmentation, which fades over time.

Possibly Hyperpigmentation, PIE if it was from a cyst acne recently, or a vascular vein issue.

Please checkout the faq top of the scar sub (First post). Goto skin then find pie and pih for some treatments. Las works best in cases like this but there are other things to try.