I don't think I would give baby asprin to a baby chick. Baby asprin are used for full grown chickens, so it will be too much for a chick. The chick really doesn't need a pain med. Just continue with the vitamins and what you are doing. Some daily physical therapy would likely be more helpful. Help him stand and walk on it's own, put back in chair. When you feel he is getting stronger, you can try the bandaid method for splayed legs on him. That way his strong leg will help keep the weak leg in place.
