HOW TO DETECT CANCER? Or to do exercise.

Dear Sir/Mam, My age is 33, weight is 91kg, height 5.11". How to check if i have any type of Cancer. I have a doubt because of these points. 1) My mom died of Lung cancer at the age 52 2) My uncle ( Mom's own brother ) died of Stomach Cancer at the age of 50 3) Am having pain ( burning sensation ) on my stomach from last 3 years. Did ultra sound two times. It showed fatty lever. Didn't give any medicines. 4) Have piles problem from last 16 years. Always having constipation. Tried changing my diet.always try to have salads, veggies etc. Drink 6ltr water every day. 5) Some times i get back pain 6) I get tired soon. Can't run more than 10 minutes 7) Having pain at knee joint from many years. 8) Having cough problem from 16 years ( my dad too have ) 9) Getting head ache every night before sleeping. but don't have any problem with sleep. i apply balm every night. 10) Every time i feel like.I don't have much energy like others. to lift anything or to do exercise. Please help