[Mere_de_Jambo]

I recently took Jambo for play dates at the dog park. He has met these dogs before. All the other dogs were very friendly and most them were close to his size. He stood on the pavement in the corner frozen and just watched the other dogs play. Any time a dog approached him he fled. I tried to play with him by throwing around his favorite toy but he wouldn't even go for it with the other dogs there. I would say we were there for an hour and he was being a total weanie the entire time. I could tell the experience totally stressed him out because if anyone tried to pet him, he would growl and normally he loves everybody (people not dogs). He was very asocial at the birthday party I took him to before as well. While all the other dogs were playing he was sniffing the bushes by himself.
He was even apprehensive with Teddi this time who is half his size (he's 6lbs)! It's fine and dandy when she could care less and has her back turned (she is a very calm and sweet girl) but if she took one step toward him (it may not have been to him even) he would balk.
I am very concerned. I am trying to find a little girl (wouldn't mind boy but I was advised to go with a girl just in case of dominance issues) companion for him but it is taking some time. I've taken him to meet some puppies who are tinies but he will freeze and not know what to do.
Input is much appreciated.