Have you noticed any quill loss or any bald spots where it looks like quills may have been lost? There is always a chance that it could be mites, and unfortunately I'm not really an expert in that area. My little guy Felix has been having similar problems lately. Dry skin is a pretty common problem with hedgehogs, and the problem could be caused by a few things. Mites, fungal, and bacterial infections are always possibilities. It could also just be dry skin from not enough humidity in the air, or you may just have a hedgie prone to dry skin.
The flax seed oil wasn't particularly helpful with Felix, but I know that it works wonders on a lot of hedgies here. I was mixing a full capsule of the oil into his kibble, then put another full capsule on his back. Since your hedgie is still tiny, you might not need to use quite as much as I did. Keep in mind that it will make her pretty slippery. Lately I've been using vitamin E on Felix, which has made a HUGE difference. You can buy capsules at pretty much any drug store (make sure they don't contain grapeseed oil or tea tree oil, which are both bad for hedgies). I've been putting a few drops on Felix's back and rubbing it in and his skin has gotten much less flaky.