How do i stop my twitter sending spam?

Someone sent me spam by DM (direct message) and, me being gullible, i fell for it and clicked on it.. Since then my twitter account has been sending spam to other people by DM and i can't find a way to stop it. I've tried changing my pword twice but that didn't work either. Please can someone help me stop this from happening?! I'm losing followers because of it!! :(