We walked to the park today and ran around a lot. He drank plenty of water and on the walk back home I think he got a heat stroke or something

He just stopped walking and sat down so I thought he hurt his foot since he never gets tired, he walks alot. So I made him walk a few steps to see what was wrong and he was wobbling around, I was so worried I forced water in his mouth and also sprinkled it on his back and head.
I picked him up and he was so limp, I used a hat to keep the sun off his head. I was so scared and carried him the whole way home, he drank a lot at home and he's fine now, fine enough that he's getting in to stuff lol, I keep telling him to go lay down
http://i23.photobucket.com/albums/b3...ead8be6312.jpg http://i23.photobucket.com/albums/b3...6132ce82cb.jpg
His left ear flops when he runs lol
http://i23.photobucket.com/albums/b3...963cc5476e.jpg
This is when I picked him up, he looks so sick
http://i23.photobucket.com/albums/b3...ca61d2aee5.jpg