red pimples then a rash

i got a new pit mutt given to me by a hina, this dog is four months old and never was taking out to walk or run. Half a mile and hes sounds like he dieing and he barly learned how 2 run(at least for 10 sec). he barly got these red pimple like in the stomach then he scraches and become scabs. I ve been told it is allergies. if it is i found out why, i feed them crap, i got purina, a 55 pound bag but as soon as that gone im getting royal canine or nutrio which one is better? (might have spelled it rong)but these scabes are worrying me help.

 

if your money situation permits it...dont wait until that bag-o-crap is empty...switch now. also...have him checked out for 'Sarcoptic Mange' commonly refered to as 'Scabies.' he's a pup...so he will get tired quickly...but if his fatigue and athsmatic-like symptoms are really bad...schedule a vet visit...and check out his heart worms.

 

k thanks, ill wait for the crap food to be emty 10 lb left so after that ill go and buy the real food, dont like to waste.