If he's constipated you wont see him pooping. You can try feeding a peeled boiled pea (the same kind we eat) to help push things through.
Here's a little info:
Swim Bladder Disorder/fish constipation:
Symptoms - Both of these have identical symptoms, but fish with swim bladder disorder generally do not survive. So your best bet is to treat for constipation and hope for the best. The fish will swim erratically, and appear to have difficulty maintaining its equilibrium. It may appear buoyant at the surface of the water, sometimes swimming in circles.
Treatment options - Feed 1 or 2 peeled boiled green peas (same kind you & I eat). Repeat daily even if the fish’s condition improves. The fiber contained in the peas will help “push things out.” If dealing with a fish that refuses to eat, you can try Epsom salt (as a laxative) or an antibiotic such as Kanamycin (aka Seachem Kanaplex) that lists diarrhea as a possible side effect.
