We have an American Bulldogges named diesel that had a similar experience. The doc saved the blockage for us to see. It was a towel of some sort that had divided itself into two parts, connected by an elastic hair band. One part was in the stomach, the other had moved into the intestine. He couldn't throw it up because of the part in the intestine, and couldn't poop it out because of the part in the stomach. What a mess.
Glad he's better!