I was riding my pony 2 days ago for about 30-45 minutes, just doing normal flat work, a bit of cantering but mainly trot and walk. He was pretty excitable and did a few cheeky bucks (he hasnt bucked in months!) Anyway towards the end I was about to cool him down and in trot he all of a sudden started putting his head down (almost as if he was fighting the bit) but I knew he wasn't himself so I walked him and tried again to see if he felt lame and he did so I got off and walked him round to cool him down but when I got off and trotted him there was no visible signs of lameless. The next day my part loaner was up so went up to I checked his leg and there was no swelling or anything and he seemed sound, she was riding him for about 15 minutes with just walk/tiny bit of trot/ canter he was fine then all of a sudden he was putting his head down again and he looked uncomfortable. So she got off him and I led him round and trotted him on a straight he seemed fine. But then I decided to try on a circle, that's when he did his head bobbing, so we put him back in his stable. Today I went up and felt both of his legs the one I though he was unsound on was slightly swollen, from the inside of the back of the knee to halfway down his leg, on the inside only (but more to the back than the front). I walked him up and down a few times and he didn't seem lame or uncomfortable even though there was swelling there. I rang the vet and she said to box rest him for a few days, and put the cold hose on it for 15mins twice a day then put him back out and if he is fine, slowly work him again in ridden work. But if he goes lame then to call her.
I'm guessing he strained a ligament or tendon of some sort whilst being ridden that day? He was going quite on his forehand and was quite speedy..
Any advice on what it could be?