I haven't felt that way for awhile, but I'm a re-rider. I barely rode at all for about 5 years, probably got on a horse 2-3x a year. For the last 3 years I've been putting a lot of work into improving myself and by extension Soda. I don't really have the money for lessons (hopefully this winter), but I've found it very helpful to read books about riding and how to train your horse/self.
I also spend a lot of time looking into the "why" behind my horses behavior.
Soda was avoiding the bit, bracing, etc, so I researched what could cause this behavior. Ended up buying a different bit after measuring his mouth, previous bit was too small and he didn't really like it. I also looked closely at my hands and how I was using my body. The problem has mostly gone away. Sometimes when he's distracted/barnsour we still have the issue, but it's getting better and better.
It might help if you relax a bit too. Don't worry about him going around braced/inverted. Just make sure your tack is all fitting him (teeth floated too) and go on a nice walk. Stop making every ride about training or making progress. Turn it into an enjoyable calming activity for both of you. If you get yourself to relax you can get him to relax. I'm of the opinion that it's extremely difficult, if not impossible, to get a tense/stressed horse to collect.
Good luck, you guys will get through this. Just start looking at the problem from different angles!