Unknown anxiety. Diagnosed with cancer.

I have this problem since past 2 years but the symptoms has just worsen now. Since 2 years I have anxiety problem. I constantly worry over small things. My heart beats very fast and I feel very light headed and dizzy whenever this happens. Even a slightest negitive thing can leave me with a fast heartbeat, sweaty and warm body and dizziness. I don't have problems in social life. I am usually happy when people are around. But I have started to feel immense sadness when I am alone. Now my symptoms have worsen since 20 days. Since the time I have heard that my friend's mother was diagnosed with cancer. I Feel that I too have cancer. And whenever this word pops up, I start crying and get upset and think that I have it too. Nowadays at night I keep on thinking about for hours before I sleep and also in the morning the moment I wake up. I don't feel like doing anything now. I keep lying on the bed all day and do nothing. I am always worrying that I might be diagnosed with cancer.