Shih tzu little red bumps

Question
My one year old shih tzu broke out in little red bumps on his tummy, back and neck approximately 10 bumps in all.  He does not seem to be bothered by them but I can feel them and they seem to be getting bigger as the night goes on.  He is not itching them nor does he seem uncomfortable. He has no fleas and no underlying illness.  We live in Michigan andhe is kept indoors.  I wonder if it could be spider bites?  Can I use over the counter benydryl cream on the bumps to reduce swelling.  I will take him to the vet if things worsen, but hate to rush him in when he otherwise seems fine.

Answer
Little red bumps indicate some sort of allergy or reaction to a bite. Mostly fleas cause this but chiggers can also cause them. New rugs in the house are an underlying and most overlooked cause. Nylon rugs are the worst offenders.
Check around the floor for something like that. New treats might also do it as could a new food.
Keep diet the same.
If they do worsen you should take him in. One benedryl capsule might help also.