One tonsil swollen with 1white streak for 3 days. Strep was very faint positive. Is this strep its only one side and 1 streak? Pen is causing gi upset

Strep. If the strep test was positive, you likely have the infection in your entire oral pharynx (mouth/tonsils). Do not worry about what side unless you continue to have pain on one side or swelling, then you must become concerned with an abscess. If the penicillin is causing you GI upset, call your doctor to consider a change in your antibiotics.