Unknown Cause of Abdominal Fluid
I am going to try and give as much context to this as I can, as we've been to multiple vets and none seem to know what is going on.
My cat Tom is around 12 years old. He is on a monthly injection of Solensia which has worked wonders for his stomatitis. He has been on Solensia for over half a year now, and has seen instantaneous improvement on his condition, and had no issues with eating/drinking/using the litterbox.
About three weeks ago, we brought Tom to Petco's vet service for the first time for his shot instead of our local clinic (since the cost was MUCH cheaper for the same thing). At the time, he was also due for his rabies vaccine. Petco decided to give both injections to him in the same appointment (PUREVAX FEL RABIES 3YR is what the vaccine is listed as on his paperwork). About a week and a half later, I noticed Tom is looking pot bellied - like to the point he looks pregnant. He also wasn't eating much and was not pooping. We brought him to the vet, and Petco did an X-ray. They said his abdomen was full of fluid. They said it would most likely be cancer or something extreme like that. They drained the fluid and tested it and said he seems better. They suggested cancer again, but did not see any indicative markers for it (malformed cells, etc). All they found in the fluid was white blood cells. They had also conducted a blood test. They said the blood test shows high white blood cell count, high globulins and low albumin.They sent him home with antibiotics and steroids to clear up any infection if he had one that may have caused the issue.
He pooped very well the day of and the day after. But now it's been two days, and he's slightly more swollen again (not nearly as much as last time but noticeable) and he hasn't pooped. I don't want them to keep giving him meds they don't know will work because they really mess his stomach up.
Does anyone have any clue which direction I should be going? Is it normal for the fluid to build up again in a small amount?