Well, that's just great isn't it.
When my son was diagnosed, erroneously I believe, with Sydenham's Chorea at age 5 he was promptly placed on Penicillin. I was told at that time he would need to be on it until he was in his 20s. Penicillin was used as a prophylactic treatment to prevent future episodes of Rheumatic Fever. It still is I have read.
By the time he was 10 and after years of my pleading that they were "wrong!" he received differential diagnoses so was subsequently taken off the Penicillin.
So basically they were treating an autoimmune condition that affects movement, mood/behaviour and possible heart involvement with something that can possibly (emphasis on possibly) cause all the same symptoms and more except for the heart involvement.