I went out and worked with her and rode her again today. It was nice and sunny out, and she's still a furball, so I decided to take her outside to tie her and go at her with the shedding blade. She was a bit anxious being led (she does that baby thing where they crowd you for security) which I dealt with, but once she was tied out in the sun being brushed, she was chill chill chill chill.
After brushing, I untied her and worked on moving her quarters around a bit with a dressage whip. Then I led her over to the mounting block, moved her into position, and then just stood her there and scratched her. She was totally relaxed.
Unfortunately I hadn't thought to bring my tack out with me, so we had to go back into the barn to get her ready, and that's when she started wigging out and bouncing off the walls. So. Definitely a separation anxiety and/or I-don't-like-it-here thing. Whether she was cross-tied or even just placed in her stall, it didn't matter. She screamed for her friends, pawed, danced, and was tricky to handle, and got keyed up. I tacked her up quickly and brought her back out, and led her around a bit, and hand-grazed her a little to bring her back down to earth, and then brought her in to ride her.
She lined up for the mounting block first try, and stood quietly while I got on, and afterwards. Score!!!
We had a nice calm ride with mainly walk and just a smattering of short trotting, mostly using vocal cues to initiate transitions as she currently knows them better than ridden cues. She'll walk, trot, whoa, and back from verbal cues that are then backed up with the riding aids to build that association.
I untacked her in the barn afterwards, where she was still antsy but nowhere near as bad as earlier. Had her move over to respect my space a couple of times, then gave her a big handful of hay and some good scratches before I turned her back out.
Very interesting learning experience today! It's definitely being in the barn away from her buddies that's getting her head spinning. She was fine before, and she was fine once she ramped down from it.
I'm going to, in the short term, do tacking up outside whenever the barn is empty, and do the untacking and let-down as a short pleasant time in the barn, post-ride. Start working on that being a place she can wind down instead of winding up!