Okay the good news is that Chrome does not have a broken or fractured jaw. In fact he doesn't have any cuts or broken teeth or anything. I really didn't think she could do that much damage with her hock at such close range, but better safe than sorry. I did find out why he was drooling and why he's sucking his cheeks. The hay we've been feeding has bristly seed heads in it that are irritating his gums and making sores in his mouth. :( I had no idea it could even do that because we've never had a problem with it before.
The veterinarian said it is a completely individual basis. Some horses have no problem with it and others do. He also gave us a number where we can get some pure Bermuda hay that won't have the seeds in it. He's also back on an antibiotic both for the sores and for the respiratory infection. Poor guy. I think I'm going to look into some sort of natural immune boosting supplement. I hate using antibiotics so frequently! The vet also suggested we rinse his mouth out with water a couple times a day to help get the hay out so his gums can heal. I'll keep everyone updated.