Okay, that's technically the opposite of what I have going on, but now I know what causes it. My incredibly tight neck and shoulders are back with one muscle actually seizing up. The good news is that I am no longer wondering how this happens. It's fear. I hold my fear in my shoulders and neck, in frozen, tight knots.
I had my lesson today and though the pony wasn't worked yesterday, I was determined not to 'over lunge' her before I got on. She seemed forward and submissive enough that I only lunged her for five minutes. The first thing Tessa did was try to say no thank you to my leg. Then she tried to say No! to my leg. Then she tried to say EFF YOU LADY to my leg and the whip. So after sitting a monster buck, we had our forward trot. I tried to breathe deeply and get back to my happy place. I lost her attention to something outside. I tried to bring her nose in to the inside, to get her focus back on me. She wasn't having any of it. And then we were off and running. What I should have done was let her run. I mean, I'm working on forward right? But I was scared. So I tried to bring her back down, I used my left hand to tilt her nose in (basically doing a one rein stop) while she galloped a small circle. I let up and she bounced away, her body tense and coiled and ready to gallop at the slightest provocation.
When we were past that, I wanted a break. I wanted to walk. I wanted to cry. I wanted to quit. However, Laura wisely kept me trotting and working, reminding me to breathe. We worked through it, we had lovely work later in our lesson where we worked on controlling the shoulder. We also got to the next level in evasions. Celebrate! I will take a horse grabbing the bit and diving (especially a little horse) over throwing their head into my face and hollowing out their back. Bring on the nose to the ground!
So, I will be taking some ibuprofen tonight and doing some stretching for my poor, sore shoulders. And I'm going to work on consciously not tensing my shoulders when I'm scared. I'm not sure exactly how I will accomplish this since I do it unconsciously, but knowing this is the problem is a damn fine start.