Hi, was diagnosed with tonsillitis yesterday and given a 10 day course of antibiotics - penicillin. However this morning my tonsils are black?!

Side effect. Some people have tongue, throat, or tonsil discoloration when they take certain medications, including bismuth (pepto-bismol) and some antibiotics. If your tonsils are no more painful, you have no new discharge or foul odor, this is most likely a side effect of the medicine. You should keep taking the penicillin, unless you have any above symptoms - then see your doctor again.