I have a 7 year old part miniature schnauzer/part miniature poodle, roughly 18 pounds. Since about 5 am this morning, (now 9 pm) he has been whimpering and yelping for no apparent reason. He has also been gnawing at his tail right in the crease of the underneath part and next to it. That area is now hairless and has tiny sores on it. He has been very withdrawn wanting to be under the bed, and has no interest in going outside which is usually one of his favorite things to do. We have given him 25mg of Benadryl (around 6 pm) since that has been prescribed by a vet in the past for a backwards sneeze issue. He has never experienced any symptoms like this before. I am just a worried dog mother wanting any advice to help him.