Sparkler's not behaving

It's Sunday so I got up early and swept the loafing shed, shoveled, then groomed Sparkler. We went to the arena and saddled up when she started to get stubborn. I checked for rocks in her hooves. She picked one up last week and was limping a bit before I found it. Not that. I decided to go outside to the front pasture and ride. There are bees everywhere and she refused to go. Not only that but there are thistle stalks that I'm sure prick her legs.

So we went back inside the arena. She became more obstinate and started crow-hopping quite a bit so I got off rather than have an incident. We did some ground work and she was fine and responsive, so is the bit is bothering her? She keeps pulling and chewing on it. Is it the arena herself? --the saddle? Or has she just got my number?