Hello, I read your message and understood your medical problem. Amoxicillin is an antibiotic corresponding to the penicillin class of drugs. If you are allergic to amoxicillin you probably are allergic to all penicillins. It has many side effects but most common are hypersensitivity reactions that are mainly expressed in the skin. This happens typically with those affected by the kissing disease or mononucleosis. It is very probably that you had mononucleosis first accompanied by a strep throat infection after that. Skin rash is a symptom of mononucleosis but is also a side effect of amoxicillin. The maculopapular rash is a very common amoxicillin skin reaction. It appears like flat blemish or discoloration areas(macules) alternating with elevated lesions (papules). The acne you are developing now may be a skin infection. The lesions first caused by amoxicillin skin reaction got infected and caused real acne. Contact a dermatologist to identify the exact cause. Amoxicillin is not the cause of the recent acne. Amoxicillin rash usually goes away after the drug is stopped and no need for other drugs or topical creams to use. The brown patch will fade away on its own after some time. Acne can me treated with local antibiotics or oral. Amocixillin is used to treat acne too but in your case it is contraindicated. You can use over the counter drugs like benzoyl peroxide or salycilic acid to treat acne. If acne does not dissappear after the use of OTC drugs that specific antibiotics must be prescribed. A dermatologist will decide for the best treatment for you. Hope this is helpful. Dr.Albana