Cat has green liquidy/soft poop, what to do?

My cat is about 8 months, he was a stray we took in & got fixed. We had no problems with him until recently. A few weeks ago he started leaving poop droplets everywhere & was leaking from his butt. I took him to the vet & got medicine (some liquid & fortiflora). The vet said it seemed he has pus in his stools & could have an infection. I gave him the medicine and kept him isolated but his poop never really got back to normal it's still been soft and kinda yellowish. Yesterday his poop was just liquid & green, so I got some anti-diarrhea medicine. I'm not sure what to do anymore. He has only been wormed once idk if that might be a problem. Or if it's just his food but he was fine until recently.