Hamster has Mites or Fleas???

[josiemv09]

One of my newest dwarf campbells that I got last weekend has either mites or fleas(I believe flea because it was easy to see)....What do I do! How do I get rid of them??? I saw him in his critter sand bath scratching and biting away like a dog...Help please! bedding change?? medicine on him??? I got him from petco. I saw online I can apply a solution of listerine, witch hazel and water to the fur..not soaking it. But..How often would I have to completely change the bedding until the mites are gone??? What should I do? People tell me to return him...but I don't have the heart, especially with Petco corporations probably sending them back to die. We don't have any exotic vets here where I am from. So...home will have to do!