Suggest Medication For Skin Rash

i was on flagyl and augmentin for a week then i developed this itchy rash that started on my arms and spread throughout my body. i took claritine tablet but did not work. i took a terracortef injection but nothing happened. i called my doctor who asked me to stop the medication. it s still there.
how long does it take to fade if i take no medication?
should i take an avil injection or take claritine and continue on it or leave it to fade on its own