Stick to natural methods if you can. Natural soaps and even castor oil helps. Our local Heath shop sells natural soaps made the old fashioned way, you get a huge bar for only a couple of dollars and it last for ages. Goats milk soap (natural) works great, plus oatmeal socks in the bath too. Google how to make these, they are fairly simple.
Sorry, Vaseline is definitely a no go zone. You wouldn't rub petrol on your skin, and it is getting absorbed straight into the blood. I have studied this as I used to make my own natural products. The amount of dangerous ingredients they put in creams and soaps is just scary!
My niece had it bad, and they found removing diary like yoghurt from her diet helped, plus no flannel sheets or pajamas. Cotton is best. Overheating especially at night flares it up.
It takes time for it to go down but yes she will grow out of it. My niece did. Besides some dry patches, it's pretty much gone.