OK so with these symptoms and his breed my primary concern is going to be some type of back injury or pain. He didn't necessarily do something like jumping off the furniture and crying out, they can be walking around the house and have a disc herniation or injury because of their anatomy.
Here is more information on this condition:
Ideal is to have your veterinarian evaluate your dog to definitively diagnose the problem and start on appropriate medication to control the discomfort. Until you are able to do this please restrict activity (which often they are already doing themselves but that means no steps/ stairs and only carrying to go potty) and rotating warm and cool compresses on the back in ten minute intervals to reduce pain and increase blood flow.
You can also do light circular massage up and down the back to stimulate blood flow if this is not too painful and will allow it.
To pick your dog up please use one hand between front legs and then scooping behind back legs to avoid pressure in the middle of the back. I have actually trained my little dogs to put their front legs on my forearm to minimize pressure on their backs and the associated discomfort.
Please let me know if you have any additional questions I can assist with. I hope you are able to get your little one comfortable soon, truly.
If you have more questions or if I can help in any other way, please do not hesitate to ask! If you would like to accept my answer, please press RATE OUR CONVERSATION (I am not compensated in any other way). Bonuses are always welcome. Thanks!
If you have additional questions after you rate the question, you are welcome to request me for additional conversations if I am on-line or by beginning your question "Dr. Altman..." or "Dogdoc4u..." and others will leave the questions for me. Good luck to you both!!!