Hi there Bharath.
Please stop using Selsun
on the face immediately!
I cant say why the rash/peeling started but it certainly will get worse with application of selsun on your face.
As first aid
measure, take a fexofenadine
180mg tablet orally once/day & wash face with plain water or a mild cleansing agent like Cetaphil
Please dont decide for yourself if things work well or not..go visit your friendly neighbourhood dermatologist
& all will be well soon!
If it is itchy for a month, then do visit the dermatologist & stop taking short-cuts!!
Cheers & Good lUck & wish you a clear countenance soon!
Dr Praveen Rodrigues MD
Vikram Hospital, Bangalore, India.