Child with strange behavior and mentality. Way of treatment?

I have a daughter age 6 yrs.From last six months she is going through some problems. She has lots of questions or might be thoughts in her mind. THOUGHTS ARE LIKE :- 1. She think she has kissed someone. 2. She has eaten dirty things like susu , potty and dirty water. 3. She wanted to cut the wrong part of men. 4. She feel like abusing. 5. She wanted to kill her mother and herself by pressing her neck . 6.She also started washing her hands many times but now she doesn t do that..and many more which I have forgotten. She hasn t done any of these things.Just used to tell her mother in words only.I have asked her do you feel like doing these things., she say no it s just coming in her mind. Her problem has started by repeatedly telling her small things to her mother and she doesn t feel satisfied till her mother says that it is ok. ONE THING IS IMPORTANT THAT SHE TELLS ALL THESE THINGS TO HER MOTHER ONLY OTHERWISE SHE IS FINE IN HER SCHOOL AND OTHER CLASSES AS I HAD WORDS WITH HER TEACHERS ALSO. We have consulted a doctor also and he had few sessions with her. After few sessions she was fine for a month but from last few days she has again started.She herself knows that these are wrong thoughts and really wanted herself to get rid of it at any cost. we havent given her any medicine but the doctor now feels that he might have to start after few days kindly suggest what should we do