I don't go to dog parks. They were created for the humans, not dogs. Most of the time they are just free-for-alls with dogs who are amped up w/ pent-up energy and owners who usually don't have a clue about managing a dog.
There are other ways to socialize a dog. I decided that introducing my dog to a strange, ever-changing pack is not one of them.
I don't think there is anything really wrong with your dog that needs fixing. What is wrong is how unnatural dog parks are as a socializing ground for our companions.
Do a search on how to socialize your dog and I reckon there will be good advice that pop up here. Good luck! It is all about learning.
Janka vom Grunenfeld, BH (d.o.b. 10/12/07)