This seemingly popped up out of nowhere.. when I attempt to do a hamstring stretch now, I get a lot of stiffness in my hamstring (but no pain, just inflexibility) and pain in my quad & glutes. It's gotten to the point where I cannot stretch my left hamstring if I wish to stand up afterwards. It's mostly only in my left side, but my right side has started seeming a little off too. I looked up some stretches to isolate the quads/glutes, thinking they had just tightened, but I did those stretches very easily with no pain. I tried just resting, that didn't really make it any better.
The only thing I can possibly connect this to is an incident with a horse which involved me landing quite forcefully on my back.. I had back pain for a week or so but it went away, and the glute pain replaced it.
I don't know what caused this, or what I should do to fix it.. I don't really think it's an injury because it doesn't bother me when I'm on land, it only comes up when stretching, skating, or doing one-foot squats.. input?