I kinda know what you are going thru... Gremlin loves to go to the dog park and play fetch with HIS tennis ball. I say it like that bc we always bring HIS and he always makes sure he gets HIS. This guy bought a very large looked like a doberman mix to the park that had a shock collar on... which kinda made me nervous that this large dog had a shock collar on and yet he let her loose. Well the doberman took grem's ball. and grem dealt with it for a min... mostly just whined to me. i took it away from the dog (the owner did nothing) and threw it for grem again. well the big dog took it from grem and grem tried to take it back and the big dog growled at him and grem growled back. He is very territoral about his ball. Well at this point im freaking out and runnin that way bc this dog could eat grem in a sec. The other dogs owner does nothing. So i had to seperate them and thought i was going to get bit myself. I didnt thank goodness. I hope your bite is ok. But i suggest some small group socializing with bigger dogs first maybe even in their territory bc sometimes gremlin thinks the park is his and gets a bit mean. Grem's fur-brother is a daushaund (which isnt big but bigger then gremlin) And he does alot better with larger dogs. As long as they dont come between him and his tennis ball.
Sorry i was kinda-long winded on that....