SO -- odd diagnosis.
He tested positive for Lymes disease. She said it can take months to show up so it was probably a tick from the summer. She said that's probably the cause for the lameness/joint tenderness in his leg. She said his hurt foot was bigger than the other and more swollen.
I was almost tearing up when he was on the table, on his back, and she moving his leg up and down and he was just crying and yelping, spazzing out. I felt terrible and wished I could do something! But overall, he was a VERY good boy for the vet (which is unusual for him) and continued wagging his tail throughout most of the process. Like he knew they were going to make him better.
She took x-rays from 2 angles of his leg and said nothing was broken. His patellas look GREAT and healthy! She also commented on his healthy white teeth.

The vet said there is around a 4% chance of kidneys being affected by Lymes and asked if I wanted to send out bloodwork to a lab but I opted not to, it was an extra $90 (on top of the already $350 vet visit!) I figured I could always do it at a later time if necessary.
This was actually a new veterinarian office we went to as our regular vet could not take us until 12:30 and that wasn't going to work with me needing to be at my dad's courthouse wedding at 1:45. I liked this vet much better, and so did Jackson. So I think we're going to switch him permanently.
She prescibed him 14 Doxycycline 100 Mg pills and I give him 1/4 tablet by mouth every 12 hours. Also, gave 7 25 Mg tablets of Rimadyl for 7 days for pain.
Whew! That was an experience. I'm just glad it's not a broken leg, luxating patellas, or something more serious.
Seven days of pretty much no activity besides bathroom breaks and he should be good to go.