Both of his breeds are prone to joint problems, and being overweight certainly doesnt help. Dry skin is probably food-related. What do you feed him? How old is he?
It sounds like he is in some pain. Time for a visit to the vet. They can give you something to help him, pain meds, or a supplement to ease his joints.
Be wary of any diet food they try to sell you. Vet foods tend to be overpriced and low-quality. There is lots of info in the food forum here, and many helpful members.
Harley & Sophie
Sid, Bandit, Mysti & Stan