While you are waiting for the cause to be diagnosed you can give him some relief with junior benadryl. 2.5mls twice a day for a dog up to 10lb.
When Lola was spade she was going nuts trying to get at the stitches as they must have been itching her (had I known it was that at the time I would have saved myself an extra $85 in pain meds
) one dose of the benadryl and she was SO much better
might give a little relief until you find the cause
Mum to Autumn 5, Evie 3, both of the human variety
Taiji age 10, of the feline variety
Ziggy age 3, of the reptile variety
and Lola age 3 months, of the fluffy bichon poo variety