Chewing his feet

Our GS has been chewing his feet but I guess I have noticed how bad it was until we have him a bath (that’s why he’s tied to the porch)

Why is he doing this? He doesn’t have fleas or ticks. We haven’t been giving him enough attention since we are both at work and have a 10 week old. But... he still gets loved on. I have no idea why he’s doing this. He’ll be a year old next month. And yes, he has bones he chews on. He can’t have toys because he’ll eat them and get sick. Even the “unbreakable” ones