Aggression- What to do?

[Emma]

My wether has been getting quite aggressive towards me lately, he's fine with other goats. Posturing, blocking my path, raising his hackles, etc. This started about three months ago. Each time it has happened, I get right on top of it. I've tried squirt guns, dumping buckets of water over his head, flipping him, a good knee to the ribs -hard-... none of it seems to be working. When I get after him he tries to headbutt me, getting more aggressive. By the end of it he gives up, but the next day he starts all over with it... This came out of no where, he was great before, really respectful and sweet. The few times I've had him out on the trail he's been great, follows along well, isn't aggressive at all. When he's not being aggressive, he's incredibly sweet. He isn't as bad when I get him out for walks, but I can't do that every single day. He's a yearling, so I hope he may outgrow it, but it doesn't look like it's a phase. If I didn't need him as a companion for my buck, he'd be out of here by now. If I have any bucklings I like born next spring, and he hasn't straightened up, he's going to have to go. Is there anything I haven't tried? Anyone have any stories of goats that were a huge PITA and worked out? I really want to make this work if I can, he's my baby, but it's so frustrating.