Hello and welcome to Healthcare Magic
It appears that you could be having an anxiety disorder, which could be causing you excessive worrying and fear of having diseases. Since this anxiety is causing you significant problems like inability to concentrate and excessive guilt, you may need professional help. There are effective treatment options - in the form of medication or counselling
which will help you overcome these fears and negative thoughts. So, I would advise you to consult a psychiatrist
for a detailed psychological evaluation
and further management.
Dr. Sheeba Stephen