My Grand-daughter Has Constant Leg (calf Area)- She Has Huntington

My grand-daughter has constant leg (calf area)- she has Huntington chorea- today Dr. Ordered neurotic 3 x a day-- she is 34 yrs. of age-extr strength Tylenol don't help at all - tried to look it up but I think I am spelling it wrong- I want to read about this medicine b/f giving it to her. HELP and thank you