I have this fear of getting a blood clot in my legs. Last year my mother passed away unexpectedly from a blood clot that broke of and went into her lungs. Recently my anxiety has gotten bad. In the calf of my right leg I have this terrible pain that hits and goes away. A cramp like feeling. It happens mostly at night. I don't have any other symptoms along with it. My question is if it's a blood clot would the pain be constant? Its pretty much only at night when I go to bed? It's keeping me from sleeping, and I've had a couple of panic attacks. I have been to the ER a couple of times since Oct and they did blood test and ultrasound of my leg. All was negative, but the worry is getting to me.