My dog, nash is acting very weird lately. Can you help me?

My dog, Nash is acting very weird lately. It's December in Kansas and he used to love going outside and was so joyful. He is one years old and he turns 2 this march. Lately, he has been going underneath the dining room table and he looks like he's scared for some reason and he whines a lot when I get home and when I go to bed. He just isn't himself and I'm worried. I was wondering if you could help me. We think its the cold weather because usually he loves going outside but now he won’t move unless I tug on his leash to make him move.. and he just goes underneath the table for no reason and just barks and whines.. when I get home, he would always be by the door when I walk in, now he just sits where he’s at and just barks like he’s in pain or scared… and when I go to bed, he won’t move and he whines so I have to pick him up and take him with me.. I dont know whats wrong with him.. Someone please help

It could be a number of things, he could be depressed, lonely, or even have an underlying illness. Just take him to the vet, they should be able to help you.