Please help - cerenia / Maropitant

oh my gosh please help anybody. I just got back from emergency hospital crying after taking my cat for dehydration and they did IV fluids all day, but I thought it was so strange how he progressively seemed almost “drunk” in that he can’t stand still , can’t go to the bathroom without falling over like a drunk person and labored breathing. The doctor kept making a fuss why he can’t walk in a straight line omg omg yes he’s a senior cat but was NOT like this just shortly before we went in and they gave him multiple shots of this garbage, first thing I noticed when I got home they gave this to give him in pill form and she emphasized give it as soon as I get home…but it says for dogs , and that got me researching. And reading about others who had incredibly weirdly lethargic cats afterward. What should I do 😭😭😭😭 he can barely walk straight still.