What Causes Constant Random Thoughts While On Treatment For Depression And Anxiety?

my mind is constantly counting numbers or thinking of sounds in a random pattern. does it when I am sitting or walking. The thought patterns match the steps I take. I take Effexor 75mg, lamictal 100 mg, Xanax 1mg. I had compulsive behavior problems as child. I m being treated for depression and anxiety. Any Ideas what is going on? Can you recommend any particular medication.