thanks for writing to us.
From the description provided it could be pityriais rosea, tinea corporis
P rosea presents as red round rash with scales at margin of the lesion. Initially a single rash appears and later on multiple rashes appear over trunk along the ribs. It is a self resolving condition.
Tinea or ring worm is fungal infection
characterised by ring shaped itchy lesions. Treatment is antifungal medicines
Psoriasis - red raised lesions with overlying thick scales. Treatment is steroid cream emollients etc.
I would recommend a visit to dermatologist
for diagnosis and Treatment.
Hope that helped.