Shrimp Melt

1/4 cup butter
1 tablespoon chopped green onion
1 pound fresh shrimp, peeled and deveined
2 tablespoons all-purpose flour
2 tablespoons Old Bay Seasoning
2 cups milk
1 tablespoon celery, chopped
1 large tomato, sliced
8 slices Provolone cheese
4 English muffins, split and toasted

In a medium saucepan, melt butter and saut