Welcome! I am Dr. Altman, a licensed veterinarian and I am happy to answer your questions.
I am so sorry to hear your little ones temperament has changed abruptly
My primary concern would be his back. Especially if he is hesitating to jump on/ off furniture or going up/ down stairs. Sometimes they will walk a little more hunched, tail tucked or even walk stiffer than usual but other times there will be no other indication that this is the issue until they are seen by your vet who can hone in on the problem
Unfortunately I see this quite commonly with the breed and with the fact he is showing this symptom abruptly with everyone makes me suspicious he is cautioning you to avoid touch because he is painful
If you do need to pick him up to get him in the car please use caution. My favorite technique is one hand between the front legs and the other behind his rear to scoop him up. I have actually taught one of my little dogs who has back pain to lay her front feet on my forearm then I pick her up behind her bottom swiftly minimizing the arching of her back therefore pain
I hope this information makes sense to you, please let me know if I can clarify anything for you today
I would not advise any over the counter pain medication for him without confirming this is the issue. If there is something else going on the pain medication can make things worse and we definitely want to avoid that scenario
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