happpened to me once.
I was on a course with him, which continued for 5 months after we spilt for seemingly no reason... he was crying etc, so was i ...everyone was shocked an convinced we'd get back together but it was just tough for ages wondering if we would, we did kiss twice but then he went weird again.
really i think you just have to go through it ...though if the course hadnt ended and i didnt see him anymore i dont know how long it would have lingered...
sorry but theres no answer or trick...you just have to let it pass...and try to avoid him