Mini Schnauzer trembling
Miniture Schnauzer is 6 years old. He has only recently started at night but every night, hiding under tables or in a cupboard if open. He is incredibly obedient but will not come when asked and does not come for a food treat, so this endorses something is not right with him. He appears to tremble a little but not a lot and cannot settle. He keeps going from one open space to a hiding place. It's happened 4 or 5 times in about 3 weeks and is totally out of character.
He's had recent vet check over, all his worming and flea control tablets were taken after his first episode. Nothing has changed with health control and diet.
It's all a bit worrying really as he's a happy, obedient little chap who eats well, and regularly with two good walks a day.
Like I say nothing has changed with his care and home environment but something is wrong with him
Any thoughts or similar experiences