Have you tried putting a sweater on him at night? is it cold where u live, he might be losing body heat . Is he eating good and drinking? Had one one i was small named Sparky and he was cold all the time so kept sweater on him ..good luck let us know how he is
Always trust your dogs instinct about ppl it is always right..
I have a chihuahua who gets cold often, its cold in the winter and spring where I live so we put swetaers on her at night and sometimes during the day. However, she does not like to keep them on, so we bought and electroni heating pad that slips into her bed. We got it at petco, so it doesn't get too hot and she likes that, it keeps her warm through the night :)
"There is no psychiatrist in the world like a puppy licking your face!"
We keep our bedroom pretty cool at nite. Even our little yorkie doesns't seem to get cold. I would put a sweater on Jimmy if you think he is too cold but they also shake when they are in pain. Good idea to get him check out.