My little girls has very sensitive skin, and we have had quite a few times these things have popped up between changes, especially when introducing new foods - tomatos and anything citrus, and then also cherries got her. Also, sometimes juice, even watered down apple juice.
We found this miracle butt cream that we love and still use now ( she is almost 2), called Triple Paste it is Fregrance Free and Hypoallergenic, sold in 2 oz. tubes fo rht ediaper bag, and 8 ox. or 1 lb. jars. I find mine at Target. For some reason, it worked much better for us than Desitin or Balmex, if they are really sore, I put it by the heater vern to get it really soft and runny, and warm, then it is easier to apply without "pulling" as you try to spread it. Also, sometimes even the Triple paste seemed notto help, in that case we used old fashioned A&D Ointment, the kind that is like petroleum jelly - not the one with added zinc oxide, the one without.
Also, from the start, she as sensitive to commercial wipes, even the sensitive kind....we have only been able ot use the Parents Choice Brand of Sensitive wipes for the last few months, in fact, and then if we use them continually, she will still get red. So anyway, I have always made our own wipes. It is wonderful - money saving, and so gentle on the little bottoms - Homemade Baby Wipes.
Buy a rubbermaid container (or two - with newborns 10 diapers a day, it is nice to have one on each floor of the house!) - I got mine at Walmart - 3 qt. Servin Saver Stackable. (some of the Large Sized plastic Coffee cans would work too, after being washed out - for a free/recycled option)
Buy Bounty Extra Soft or Viva paper towels in bulk.
Take a big serrated Bread-cutting knife or electric knife, and cut the paper towel roll in half so you have two shorter rolls.
Place one half in each canister (you may want to brush off some of the "fuzzies" /lint from cutting, into the garbage first).
Take a 2 C or bigger measuring cup (get a cheapo you dedicate to this) and a Tablespoon (dedicated too) - measure out 2 Tablespoons of Baby Wash, and 1 Tablespoon of Baby Oil, and pour them in the bottom of the cup, then fill it with 2 cups of warm water - stir up the ingredients with the measuring spoon. Then pour this over one of the paper towel rolls in the canister. Put the lid on, and let it absorb....to start the roll, pull out the cardboard center - there you have it!
1/2 roll paper towels
2T Baby Wash
1T Baby Oil
2C warm water
I have been using this on CJ for two years now - when we use these, she almost NEVER has a diaper rash.
In two years, we have only used up maybe 25 rolls of paper towels, and only 6 bottles of baby wash, and 3 of baby oil - VERY CHEAP - much cheaper than buying wipes! For short traveling, we would just tear off a bunch and throw them in a ziploc, and for long distance, just ake one of the canisters full!
Hope this helps you!