A couple of things. she probably needs a good gallop to feel better, and was wondering if there was a time when other horses weren't around when you could get her moving and really keep her gong until she is winded and begging to stop.
When you ride with other horses, if you are riding in a line, then you do this: One horse leads for awhile and then that horse "peels off" and goes to the end of the line and "peels in" at the end. That makes #2 horse now the lead. and Then after a bit, peel off , go to back and keep doing this.
Helps in many ways, one because no one horse must lead or follow forever, and the action of bending (disenagaging the hind quarters) and going in a direction counter to the group getrs the horse's mind with the rider.
Do it alot.
If she starts dancing and cannot keep her feet still, understand that trying to hold them still means that she must go up instead. SO, get her moving in a circle. Let her move, since she feels compelled to move, but keep her circling or figure eights, and don't clamp down with Both reins; one rein tight, the other looser.
good luck, it will get easier, round pen will help and time. Get through this and it'll be smooth sailing!