Hello!! I have an issues of over thinking everything, which causes anxiety to me, if someone said anything or i got to heard anything...it continuously keeps on rotating in my mind,either the matter is very minor but it seems to me a very huge problem,i use to try very hard to cop up with it or  not to think of all things that happened in past but it kept stucked in my mind for 3-4 days...which ultimately cause me headache..even am very much unsecured about certain things, for example- I always use to lock my room by myself, but every time I feel like I haven't locked it, I Cross check it more than 2-3times. And due to all these issues am unable to sleep properly. Please let me know is it normal in human behavior, and if not please suggest me with solution. Thanking you