This is a tough one given you have tried everything that I can think of except a a pick. The type dentist use or even those plastic pieces with a small piece of floss. When I first say them I thought No Way! But the actually are quite sturdy and effective with mouth wash for just the problem you describe. I know I have a bridge that always seems to get the difficult piece of everything and I have to do this quite often and the dental piece with Listerine always seems to work for me. That of a few good stiff shots!
