Blood draws and appetite meds

Mac had more blood drawn yesterday so we treated him to Panera. He started a new med to help his appetite and while it helped immediately with that it also made him loopy, increased his heart rate by more than 20%, and just generally act weird. I was worried he might be getting dehydrated since we doubled his lasix. We had to pro in the office draw his blood - she was super fast and he only screamed his head off for less than 5 minutes. His Ped feels it’s the appetite med that caused his change in behavior/heart rate and we need to give it more time and he will become more tolerant to its side effects. I took a video almost 8 hrs after starting it and he was still a little manic - his sisters were calling him “Slappy Mac” bc he was acting slaphappy. He alternated between manic and super sleepy. His last appetite stimulant made him angry and aggressive so I guess silly and manic is better ...?