Blocked Brain. Havent done any check up!

I have been having this feeling where my head is completely blocked and i am not able to clear my head at all no matter how much I try, it stays that way for hours and hours and i cant even sleep sometimes, i am in that constant fear that if i sleep or rest i might lose something or something bad would happen. Also i tend to repeatedly think about the same thing over and over again and cant get over it, its really annoying specially when i am sad and emotional and i just end up thinking all the hurtful things from my past and relate my present to them and just hurt myself that way. I kinda feel its ocd but i havent done any check up regarding this. Sometimes because of all this my heart would start beating really slow to the paint where i am in a state of complete fear that my heart will blast as it starts paining, also sometimes i kind of get the feeling of cramps in my heart and it pains so much and i am afraid of even breathing scared that it may hurt.