Sir,
I have developed recently a condition where in certain instances I have noticed blood stains on my shirt resulting from blood from belly button. I deliberately eat less but have good stamina and strength. I have been experiencing abdominal pain sometimes in the past two weeks and discomfort in the belly button for the past one month. Kindly advise.

Please go to the ER and get checked, since bleeding there is not normal and this well could be very serious.

Has nothing to do with being fat or being fit, 300 lb men do not bleed from belly button

There is a rare condition (2% of population, mostly male) called Meckel's diverticulum that I would ask about. Bleeding is usually rectal, but pain is often at the umbilicus (belly button).
It definitely needs medical attention, no matter what it turns out to be.