I've noticed that he wasn't listening to my leg and just being generally lazy, but I've been working on it and he's becoming more responsive.
But now I have another problem: He is leaning into corners to the point where my leg is sometimes getting scraped along the arena fence. He turns his head in towards the centre while his body moves towards the side. He's done it before and I've gotten skinned knees, but I can't remember how we stopped it.
His teeth and tack are both fine, as it's been checked. The arena I'm working in is only a small round one and I realise that it isn't helping but within the next few weeks I will have access to a bigger arena where he hopefully won't want to do it do much. I will also be able to do more (turns, serpentines, poles) so he won't be getting bored as that might be part of the problem.
Personally I think he is just testing me. I'm the first to admit I'm not the best rider and I'm just not sure if I'm making it worse with my aids when I try to correct it. So any advice on how to stop him doing this? It would be much appreciated.