What is wrong? What do I do!?

Ok my 18 year old cousin has some mental problems and she sucks a pacifier at night. Well about a month ago she got a viral infection in her throat so the doctor gave her an antibiotic. Well as soon as they were done she got it back. Now she isnt even done with this dose yet and she is starting to get it back. What should she do? I mean I hate seeing her miserable all the time. Please help