We took Belle to the new Vet Clinic in Tucson today to see if they could tell us what is going on with her jaw. They took x-rays & sure enough, she has another smaller "jaw rock". Surprisingly to me, her jaw bone isn't deformed, which would be the case, if she had gotten kicked when she was younger. The Vet thinks maybe some of her teeth cells got misplaced when she was an embryo, & her body is encapsulating those cells & covering them with calcium. Equines can have a "rock" formation in their intestinal tract called an enterolith . This isn't the same thing, but has all the same qualities.
The Vet tried pushing it out, but this one is in a different position than the 1st one. It also isn't as large. We opted to watch it for awhile, & see if it grows, or moves, before we decide to have it removed. It may never bother her, so no reason to put her thru surgery.
The Vet also looked at her front legs, & agreed with my earlier diagnosis, she bowed the tendons in both front legs, when the neighbor's dogs chased her & Nina. She is sound on her front legs now & as the Vet said she isn't going to be a hunter, jumper or cutting horse, so they shouldn't be a problem.