You were using tretinoin ,,this is a very effective in acne and is very frequently prescribed by dermatologists...But the problem is that proper application of this topical medication
is very important..
It has to be applied only at night
Very little amount has to be applied,,and it should not be rubbed onto the skin,,,
The cream should only be touched over the affected area.
Now in your case, you developed irritant dermatitis
healing with post inflammatory hyperpigmentation
You should use a lightening agent like kojic acid
over your face twice a day over the pigmented areas..And use a sunscreen (spf>26) regularly over your face...You can also take oral Vitamin C supplementation
If inspite of the above measures, you feel that the lesions are not improving, then i would suggest you to see a dermatologist as nowadays there are various treatment options available for post acne scars like chemical peels
, lasers etc..
Hope it helps
Dr Geetika Paul