Dog Chewwing Things!?

A dog that chews their feet until they bleed is either suffering from a fungal infection of the paw or allergies. You need to have a vet check your dog for both of those. Your dog eats your underpants because dogs like funky stuff. Same reason my sister, a vet tech, sees a dog about once every week with a sanitary napkin stuck in their intestines. Your best bet would be to keep your underpants somewhere the dog cannot get to them.