You are a young fellow, active , now doing workout in Gym. I am
sure you do weight lifting , tread mill etc. This could certainly
affect the abdominal muscles causing strain and may be even sprain
Blood in the stool after a hard bowel movement is due to small piles
or Hemorrhoids (Internal or external) or may be a small tear or
. Continue to drink fluids and use an over the counter
. Your pharmacist in the drug store can give you
suggestions about this.
Wish you well.