We were treated for scabies 3 days ago ; we've noticed a few new red bumps and burrows since treatment... Has treatment failed?

Probably not. The symptoms of scabies are due to the body's immune reaction to the mite and its droppings in the skin. They are still there after treatment kills the mites, and symptoms can continue for 2-3 weeks -- in fact they sometimes get worse or new itchy spots appear for a while after treatment. See your doctor if it gets a lot worse or if you're still having itching and rash 3 weeks after treatment.