Invincible
Hi Romeo
There are several things it could be, but the only way to know is to take him to a vet (preferably holistic) and get it checked out.
I advise you to do that ASAP. Do not expect Curezone posters to be able to fully diagnose what may be very unique, and potentially life threatening in your dog.
Once you have a proper diagnosis, you can come back here and get advice (based on our personal experiences and research) - you don't have to follow through with any advice or treatments a vet advises if you feel there may be a more holistic way.
Should your vet need to do x-rays, you might like to give your dog a small amount of good quality (Norwegian) kelp powder in his food, several times a day, as this helps to move radiation out of the body.
Get to the vet ASAP! Then let us know how you get on please.
All the best to you and yorkie pup!
Maya