<s>[INST] I recently started a round of antibiotics to treat a sinus infection which caused me to have a 3 day bout with diarreah.Shortly thereafter I start to suffer with a case raw itchy skin rash just above my rectom.  What can I use to treat this painful irritating rash? [/INST] Hello,I read carefully your query and understand your concern. The symptoms seem to be related to an allergic reaction to antibiotics. I suggest using anti histamine such as Cetirizine 10 mg.I also suggest using Calamine lotion for local application. Hope my answer was helpful.If you have further queries feel free to contact me again.Kind regards! Dr.Dorina Gurabardhi General &Family Physician </s>