My black lab is having trouble breathing he only wants to lay around when he gets up he struggles and walks side ways is tongue was grey in color although it is now pink again I'm very worried he seems to be in pain he's 17 yours old and I'm afraid it time to let h go.

You need to get him to the vet ASAP at 17 he is a senior citizen.
It could be cardiac in nature, it could be other things, but mucous membranes turning gray is not a good sign and needs to be addressed.

Seventeen years is a good long life. Before you chalk it up to the end I would highly urge you to see a vet. It could be something very easily fixed. The walking sideways sounds like an inner ear infection, but that's just a guess, and that's sadly all we can do on this site, it also doesn't explain the grey tongue, or the breathing issues, which sound like lack of oxygen.

Please see your vet, and I wish you all the best. If this is the end, know that you gave him a long happy life. I wish you all the best.