So she went to the equine vet today and apparently her stifle was locking up!
Which is weird since it only happens in young horses and she's only ten.
However I was told the Telesis horses[her father is Lenas Telesis] all have stifle issues so I guess it's common among them.
Nevertheless, Heidi got blistered and I'm going to stay off of her for 3 days then I can start light arena work.
In just a few weeks, I'll be rodeoing on her again!