You should have checked for a neurological problem or a tumor.
I assume it is not related to anything in the weather, fireworks, etc?
Could be rabies or encephalitis or tumor or something really throwing him off -- check your carbon monoxide tester recently? Dogs sometimes sense things quicker than we do, weird sounds. Electrical storms, etc.
I hope you all can figure it out.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC