Help !!

11 month old mix small dog, he keeps getting this rash and it goes away but then comes back. Its spreading a little up his side. I was thinking focculitis? He scratches at it a lot which can be why its all red and nasty. I just want to have an idea because vets in new york are very expensive and im a college student.

Flea bites? Allergies?

This does look like the type of rash dogs get from flea or food allergies, and the pus filled ones may be bacterial infection.
Here is a link to a site with info on allergy and how to eliminate the cause and also treat the symptoms http://www.dog-health-guide.org/canineskinallergy.html, so maybe you can try some self-treatment first to see if you can get it under control.
Also, there is an organic supplement called Fucopia that helps greatly with skin and coat problems, particularly for allergies! It helps reduce the reaction.

Looks like allergies to me, my dog suffers a lot with food allergies and needs constant medication. Luckily she us insured because it can be very expensive. Coconut oil is very good for skin and coat health and also has many other benefits. 1/4 tablespoon twice a day. Also I like to use batch flower remedies, although I would still always seek advice from a veterinary expert these remedies can assist and even cure many problems. Have a look here... there is also blog in coconut oil benefits

Treat for fleas

If that doesn't work, try an elimination diet to rule out food allergies.

If it is allergy related, it may be environmental. Try keeping off grassed areas and washing him down after each outdoor outing.

Also, as the rash goes away then comes back again, keep a diary noting down everything he does and also everything he eats. This may be a big help in finding out the trigger for the rash