What I understood from your writing is that you are highly anxious and worried. You may not be having that many kind of illnesses as you described. I am a Clinical Psychologist
and what I feel is that you did not get psychological interventions like psychotherapy
or counselling in addition to your treatment now. Try to avail cognitive behaviour therapy (CBT) for the same. Definitely healthy diet
with fish and fish oil (omega3) will help you. Avoid direct sugars, processed food and Too much of fat. Do moderate exercise like regular walking for 30 to 40 minutes .Be busy with things and get away from negative thoughts .Bye and take care.