Mange will usually get worse before it gets better. I think Ivermectin is a bit extreme for puppy mange, especially if she only has a few spots. It is usually caused by an immature immune system that is not very strong yet. It usually just needs to mature a bit. A good healthy diet with some Vitamin C to boost the immune system is usually all that is required. Don't do anything to stress the immune system, like give vaccinations until it clears up. It will usually go away and never come back.
Good luck with your pup!
Tara, IWS 5/17/02 -
Dante, Male Brindle 3/18/10 - Adopt 5/13/13
At the Rainbow Bridge, Markus and Terramoto