If the rashes are coming ang going she might be having Urticaria and taking tab levocetrizine 5mg once or daily might help in reducing the itching. If u r planning for cure then consult a proper dermatologist.
If the patches are ring shaped, then it could be fungal and taking medications for itching wont help unless the fungus is treated.
Next Steps
visit a dermatologist
Health Tips
apply moisturiser immediately after bath on moist skin after pat drying with towel.