Dog issues

We are having dog issues. I am not sure how else to state it. As some of you know, Elvis (our Italian Greyhound), is kind of a special needs dog in the first place. He is a rescue dog who is extremely shy and pretty anti-social. But he is gentle, sweet, and loving too. Over the past 5 years, he has made tremendous progress. He has gone from not taking treats from us or wanting to be in the same room with us to curling up on the couch next to us and warming up to our friends and family. He is not normal but he is a good pet. Very quiet and generally no problem. Over the past 6 weeks he has started yelping pretty frequently. I am talking loud painful-sounding yelping that makes you jump out of your seat. I took him to the vet a month ago and they could not get him to show any kind of a pain response to anything that they did. I have been keeping track of when he yelps and there is no distinct pattern. He does it when he jumps off the couch, he does it when I sit on the opposite end of the couch and am 4 feet away from him, he does it when he gets spooked, and he is starting to do it in his sleep. I thought it might be his teeth since he wouldn't eat his Greenie last week. So I went back to the vet on Monday. She looked at his teeth but did not think that they looked too bad. We did another exam including an Xray of his spine and found out nothing. So now he is on some medicine to get his thyroid back on track before we do a dental cleaning. Kind of in a holding pattern.

This morning I let Griffin go downstairs when he woke up and I tried to rest for a few more minutes. All of the sudden I heard Elvis doing his loud yelping sound like he was in pain. He did this for a FULL five minutes. When I ran downstairs, he was huddled under the dining room table and he was shaking. Griffin was crying hysterically. I still have no idea what transpired between these two. Griffin says he was "trying to get Elvis to play cars" with him. I don't think he hit Elvis since he is always very gentle with him. But I could see him maybe driving a car by Elvis and maybe bumping him. I know something is wrong with Elvis but I can't figure it out. This afternoon I even heard him yelp as I was unlocking our front door to come home. I am starting to wonder if some of it is anxiety. As to why he does this when he sleeps, who knows? I just feel so badly that he may be in pain and we can't figure things out.

If anyone has any suggestions (Jessica?) let me know!