Hello
Welcome to health care magic,
These itchy rashes on
scalp and groin could be urticarial rashes or
fungal infection or
psoriasis but it can be diagnosed only after clinical examination of these rashes.
Since your doctor thinking them as psoriasis but if they appeared suddenly then I would more think about urticarial rashes.So,I would keep a possibility of acute urticaria first.
It presents as skin welts/swellings which can be seen commonly on hands and legs but it can also be distributed all over the body.
Itching is subjective in individuals which could be mild to severe.
Urticaria or allergic
hives can occur due to various causes like,
1) Infections (bacterial, viral, fungal)
2) Certain drugs(Pain killers/ antibiotics etc)
3) Certain foods and food additives/preservatives
You can take oral antihistamine like
benadryl or tablet levocetrizine 10 mg twice daily for 2 or 3 days.
If dermarest is not helping much then you may discontiue it.
A topical soothing lotion like
calamine would also be helpful symptomatically.
I would expect that you will start improving in 3 to 5 days and in case not,then it would be advisable to see some nearby doctor (preferably
dermatologist) who may order routine blood counts with ESR after careful inspection this rashes and can prescribe you appropriate treatment according to the underlying cause.
Hope this will help you.
Regards,