Overthinking

At one point I can be in a happy and peaceful state of mind with nothing at that moment going wrong, everything is going right when something so little triggers my mind to become depressed,worried,and scared in just seconds.My mind takes what just happened what was just heard,what was just seen,what was just experienced as a hint of whats to come.So many different scenarios run thorugh the mind so many dark thoughts,so many nightmares.I stand there beginning to stress out,my head hurts,and I become in a state of insanity.I keep asking myself "what if this happens?!? over and over.I'm shaking and twitching so much my surrounding become suddenly hot.I'm afraid if such scenarios will happen because such scenarios tend to involve things or people I care and worry about alot.It scares me even more that theres a high chance that such scenarios will occur.It scares me more that some do occur.It hurts when it does.