I know that same feeling, cause I've been (and still am) dealing with it for a long time. Most of the time, the way to clear those thoughts, is to meditate, clear the mind for a while, and constantly pray to God. The other way to clear them, is to keep your mind occupied with a job or something, and focus on keeping your mind on that, no matter how long it may be, and keep praying. Those thoughts are to keep your mind in a box, to only think about that, so you have to try to think outside the box, and are nothing more then satan disturbing you, He just mad, and wants you back, and is using another lie, and trick, to do it. Just brush him off.
Btw, if you talk to a Priest, or if you know people in your church that have the gift
of healing, ask them to pray over you, so that you can get some healing for the mind.
Just some advise from somebody who has the same problem, and found some ways to deal with them, without medication.