Seems like you developed an irritant reaction due to the cream,,this cream contains hydroquinone
+ Tretinoin + steroid..it is a triple combination commonly used by dermatologists for treating hyperpigmentation
,,,but one has to use this cream with caution..It has to be applied only at night...Moreover, it should not be rubbed over the skin ..and very small amount has to be applied...
What you have developed now is irritant dermatitis
.first of all,,stop using the triple combination..I would advise you to use a mild steroid like mometasone
cream over the affected area twice a day for 4-5 days....and use a sunscreen regularly before going out in the sun...
Once the reaction heals up , then you can start using a lightening agent like kojic acid
with vitamin C twice a day till the pigmentation improves...
Hope it helps
Dr Geetika Paul