Hello and welcome to healthcaremagic
I would think that the peel was stronger this time as compared to last time OR it was kept for a longer time than before, therefore it may have acted more as compared to last time, thus leading on to irritation with resulting post-inflammatory hyperpigmentation
Cosmopeel contains Trichloroacetic acid
) and is considered to be one of the stronger peels. The end point of cosmo peel is frosting and mild erythema
, when the peel should be neutralized, immediately. However some times the peel can act more aggressively either because higher concentration is used or it is left for a little longer than the end point, thus causing more frosting and deeper erythema and later post inflammatory hyperpigmentation.
I would suggest that you use a moderately potent topical steroid
cream, twice daily over the affected area(flutivate cream) for a few days. This would facilitate the superficial dark, dead skin peel off and would also help in resolving post-inflammatory hyperpigmentation.
Sun protection with a broad spectrum sunscreen is advisable to prevent sun induced darkening.