I only poop once a week and i always am tired? is there a problem ?

Start here...: Normal stooling ranges from 3-4x/day to 1 every 3-4 days. Your described stool frequency at once a week deserves evaluation. 1st, you are taking constipating medication? 2nd, if no tests have been yet accomplished, see a GI doctor to rule out metabolic disease (e.G hypothyroidism), partial obstruction, inflammation, anatomic defects (check colon), functional problem (e.G hirschprung's, etc.), more.

Constipation: Sounds like you need to have your thyroid function checked. Hypothyroidism can lead to fatigue and chronic constipation.