I came home from work today, and Paddington barely got up to greet me

I tried to take him outside like I usually do when I get home from work, and instead of chasing me around the yard like a hyper maniac, he just layed down at the bottom of the steps where I put him. He won't play, won't even get excited for treats OR his rubber duckies.... He doesn't seem sick; he is still eating well. He just seems mopey and sad!!! Should I be worried and take him to a vet??? I have an appointment for Saturday morning already; should I take him asap???
We went to the groomer this morning for a bath and a nail trim, and he was terrified by it. I could hear him all the way in the front crying during his bath. But all they were doing was bathing him, so I figured no big deal, they aren't being rough or hurting him, he's just being a baby and he'll get used to it... I think he is still scared. But also my brother brought over his dog yesterday at the picnic, and I know he misses being with his brothers and sisters too, so maybe he is just sad about being alone again??? He was alone when I came in; my mom and grandma must have stepped out to the store. I just don't know what is the matter

I gave him some nutrical with his dinner....
He is usually so hyper this time of day
-O