There are not too many foods that are WORSE or cheaper than Ol' Roy. If the "breeder" feeds this, I'm afraid this breeder is not good.
This could very well be the cause of your dog's problems.
Please give him better food, and continue to feed for at least 2 months to see if the problem resolves itself.
There are many foods that are good. Solid Gold is one of them.
if you have a family doller store near they have BENEFUL BY PURINA for $4 a bag (4lb)
In addition to this being crappy junk food, foodstuffs at dollar stores is often way past the expiry date.
If someone cannot afford to feed their pet properly, or get it adequate medical care, I question why that person would have a pet at all.