Dangerous Fear

I am 47 and have severe health anxiety since last 15 years and was diagnosed mitral valve prolapse with trivial regurgitation before 6 years. All this year my fear was related to heart disease, attack, stroke arrhythmia, nuero problems etc. but one week before urine came from my blood and got scared and went to urologist and did ultrasound for kidney, prostate, uterus etc and there was no stone & infection. The Dr. gave me antiobiotic & told to complete the course. Since one week I got afraid of Cancer, which started with this infection & all of a sudden I remember one of my aunt who died of cancer, she was having blood in the stool. I started to look at my stool everytime & fearing that there is blood or my stool is black & I will get or have some sort of stomach related cancer. I am afraid to go the bathroom for my poo, even small belching, bloating, gas makes me afraid. How to fight this fear. Plz help me I am dying of obsessing this stomach cancer fear. I know that, this is irrational fear and blood can come by ulcer, anal fissure, inflammation of the colon etc.My anxiety is very severe and I am unable to relax or sleep. I am taking cipralex(escitalopram) 10 mg including .25mg rivotril 2 times since one week and also taking bisoprolol (beta blocker) 5mg for my blood pressure. Please someone help me to desensitize this fear, if I am unable to remove the fear, my heart problems will be increase.