Get him checked out!!!!!
My dog is in the vet hospital as we speak .............. was out with him last night, too many runs (didn't seem like that at the time though).
Walking across fields back to the cars, my dog was lagging behind, kept an eye on him, next minute he starts walking really slowly and robotically, then collapsed.
If it hadn't been for the bloke I was out with helping me carry him and for the keeper who came to collect us for the last few fields I wouldn't have the dog today.
Can't believe how quickly he went down, tried giving him water, he wouldn't/couldn't s