It feels like the main vein in my inner thy is going to blow up, it lasts for 5to7 minutes about two or three times a month ,it isn t muscle cramps ,it is my main Vein on my inner thy ,where I feel if it bursts inside my leg will I bleed to death, the only way I can stop it is to stand if I can,it emobluzes me. What is causing it. PS. I think I also have heart damage