Daily panic attacks. Me what to do.

I am addicted to recurrence of negative thoughts from last 15 years. I become panicked like this illness cancer aids may not happen to me by seeing small gland in throat which is already checked and found nothing but doubt is always there or by cutting hair on a barber with new blade or used blade. Why we are doing all the work one day we will have natural calamity and everything thing will be ruined down.Then I start taking tension I got heavy brain with headache for last two years which makes me uncomfortable and in the same situation from last 1years I have chest pain headache arm pain back pain heart beat rate increases. I continuously engaged in these thoughts which become my life sad and unenjoying. After periodically 1hr I get panic attacks like I am going to to die or will get heart attack. This cycle repeats around 3-4 times daily. Some times pain start from arm travel to back. Once I control my mind then I think it may come again. Suggest me what to do. Thanks