Now, this is digging back into my memory a few years...
I once turned up for my riding lesson (pre-horse-owner days...), and started to get my usual lesson mare ready. Her bridle was really worn, so my instructor had sent it away for repair. So, instructor hands me another bridle that had a slightly different bit on it. The mare was normally ridden one handed on a very loose rein in an American TT, but this TT had a slightly longer shank, and was stainless steel, as opposed to the mare's normal copper mouthpiece.
She reacted exactly how you are describing. Throwing her head up and down, doing a bizarre kind of Spanish Walk looking thing, the whole bit.
We ended up taking the bridle off of her and riding her in a halter and 2 lead ropes until "her" bridle and bit came back.
I'm not sure what to tell you, but I have seen a horse react that way before.
A stubborn horse walks behind you, an impatient one in front of you, but a noble companion walks beside you ~ Unknown