Ankle Horse Boots

I fell off my horse about 12 hours ago (he's an ex racehorse, got overexcited, bucked and I came down).
I can't remember how I landed, but I had immediate knee pain. I hobbled back home, mounted again (with the sore leg) and rode for 5 minutes before putting him away.
When I got home I took my riding boots off, and realised my ankle hurt too. I've been hobbling around all afternoon on it, but now it's gotten to the point where I can't bear any weight on that leg. There is only very mild swelling in both the knee and the ankle.
I can bend my knee, but not straighten it, and it is tender to the touch, with bruising above the kneecap.
The ankle is tender on the inside to the touch, and I have very limited movement, and sharp pains whenever I try to stand on it.
I normally have a pretty high threshold for pain, hence hobbling around lots, but now I'm concerned! Would my ankle be broken?