If horse is getting like this, he may need more work on basics, such as responding to you, and following your directions. He may also be getting by with things without you realizing it is happening and that is now leading to him testing you to see what he can get by with.
He sounds like he is getting barn sour to me. Doesn't want to work in other words. These little "Oh I am scared" fits are teaching YOU that he can't be ridden outside of one area.
If he is pushing you out of his space, with even his head, or getting too close to your body, that is a sign of disrespect, and also shows he thinks he is the leader. If you pet on him, and baby him, that is not good either. If he is aggressive at feeding, or can't be led well, that too leads to problems. If you groom him or mess with him without his halter on and a lead attached? That also lets him think he is in charge, since HE decides when to walk away.
Not knowing how strong a rider you are makes me hesitant to suggest to you what I would do. I would have a riding whip and pop him one, but he would go where I wanted. At this point he is telling you, "You can't make me" and it can escalate to where you can't do anything with him, much less ride him outside of where he wants to go, IF he wants to that is.
You might also be seeing the effects of spring, and grass, or if he is stalled and grained and hayed, it could be that is too hot for him, in terms of gives him way too much enthusiasm about finding reasons to act up.
Horses make me a better person.