2 yr old was given rx permethrin 5% 2 days ago. after applying developed a rash even worse than before treatment. is she allergic? can i use calamine?

Calamine ok: The reaction was likely an irritation especially when ther e has been no itching. Topical hydrocortisone may help but consult a doctor if problem persists.

Yes you can: Works well for scabies. If some reactive dermatitis, the permethrin may not work. I would have it looked at again and may recommend Hydrocortisone cream instead to see if works.