My approx. 2-3 month cat doesn't poop or pee, I think.

Yesterday I took in a small kitten I found on my way to work. A friend took it to the vet for me (I couldn't leave work) and the vet gave eye droplets for it because it has mild cat flu. However.. I've fed it several times since, it drank water this morning, and it doesn't seem lethargic or anything. It purrs, it clings, it runs around and stuff.... It just doesn't seem to poop or pee at all. I can't find anything, I can't smell anything, my mom doesn't smell anything, it's tummy feels full to the touch... I got it yesterday I fed it at 8 in the morning, it's now 7:30 in the morning... It's basically been 24 hours.