He recently had an accident on the trailer, he stuck his head between the dividers and cut his eye open. He needed five stitches at the show, but he was also given a natural relaxant before he got on the trailer so I don’t know what he was doing.
Hmm... was he ever in an accident with past owners? Or did past owners force him on the trailer? Maybe just start from the beginning and essentially retrain him. Get him near the trailer and let him graze and relax. Then slowly get him closer to the trailer and eventually on it. Hope this helps and good luck!