5 month old chihuahua. He is losing all his baby teeth. His gums are so sore looking and he's really off his food. Had pups before but never had one have such a hard time with teething. He hasn't eaten anything at all today, his tummy is rumbling and gurgling so he must be hungry but won't eat. Is there anything I can give him to ease his pain? He won't chew on his chews either as it must be too painful for him!