Won't eat or drink and very nauseated

My 10 yr old Egyptian Mau stopped eating and drinking 5 days ago. He vomited once day one and multipe times day 2 and 3. It seemed like he was very nauseated because he would only throw up after moving around. He got an injection for nausea on day 3 and has not vomited except for a hair ball until tonight. Day 3 and now today day 5 we took him to the vet? Here is a list of what they checked: blood chemistry panel in house, CBC, radiograph (2-3) views, and a PLI to Idexx (blood test for the pancreas). Everything came back fine but we are still waiting for the PLI blood work. He received fluids and cerenia for nausea on day 3 and today. I gave him 1/4 of a tablet of mirtazapine tonight and he perked up and actually ate some wet food. In 30 mins he vomited it all up and just moaned and cried and layed down or walked around for 10 mins. He went to the cat box and pooped a small amount but was still visually in a lot of discomfort. He finally calmed down. It's been an hour now and I hear him walk over to the dry cat food and eat some. I am so confused! I just don't know what is wrong with him. Any help or thoughts would be greatly appreciated. Side note he chewed on the leaves of a alstromeria flower which I read can be mildly poisonous. At first thats what we thought it was but test showed otherwise. No liver or kidney issues.

I am so sorry for your kitty's distress! Has he been able to keep anything down? Has he ever had problems with hairballs before? Does he chew on plastic sometimes? Because neither hairballs nor plastic show up on x-ray. Perhaps it's time to move on to an ultrasound, endoscopy, or barium study? Were these mentioned? When our kitty had similar problems, the next step was ultrasound, and if nothing was found, a barium study. Nothing was found on the ultrasound, but as she was keeping food down at that point, we didn't do the barium study.

Vibes for your boy.

I agree that you should have an ultrasound done and very, very soon. You need to pinpoint what's going on before his liver starts to develop hepatic lipidosis. Make sure it's a board certified, licensed ultrasoundagrapher. I'm guessing if all the blood work came back fine but you haven't received the PLI yet, he could have pancreatitis. I think they also need to check for any obstructions, it sounds like that also could be a possibility.

What did your vet say about the ailment?  Did he/she think it may be poison or something else?  I think if no improvement an ultrasound might be in order.  I would certainly be in touch with the vet again and get some concrete answers about what he/she thinks this is.  The lack of drinking would worry me.  It does sound like he might be regaining interest in food.  Please keep us posted.