This is a common question and after years of helping people with this painful issue, I feel confident in my answers.
This becomes a two part answer and both of these changes will change your life and your comfort level. I've seen some pervasive and cystic type reactions from chub rub.
*First: Stop the soap and start using a high grade body scrub- most especially on the areas where you're having issues, inner thighs, under breasts, in those luscious fat creases. Oftentimes we don't realize that not only is soap closing off pores in an unnatural way, it is also getting more stuck in these areas. Did you know that if you read the Material Data Safety Sheet on soaps (especially those used in gel and liquid soaps) it says to rinse for 5-10 minutes solid on the area where you applied the soap??? It doesn't say that on any of your bottles and it certainly doesn't caution you whatsoever about any minimum rinse time.
This is because these surfactants very commonly cause rashes when even a small amount is left on the skin. Many of them also cause cancer when left on daily!! We not only don't manage to rinse it all away, but it rests especially securely in every place where our most sensitive skin is located.
**Body scrubs with shea butter and good oils open the pores, pull out trapped debris and allow the body to properly let go of toxins that it's trying to sweat out. Soap removes whatever is on the top layer an squeezes closed all those precious pores that are just trying to do their jobs.**
SECOND: Use an oil based, water-free moisturizer on these areas at least twice a day. You don't want MORE water in these areas, you want glide, baby! My SHU Healing Moisturizer and the body scrub switch with a scrub that includes shea butter and coffee is how many have gotten rid of not only the painful rashes, but also deep cystic acne that can come up especially between the thighs as a result of the constant pressure and rubbing.
I've seen a lot of products that dry the area with powders and provide some temporary glide, but nothing is as effective and good for your skin as pure oils. Also remember that all carrier oils and butters are naturally anti-bacterial and this is an added bonus.
SHU Healing Moisturizer includes Ucuuba Butter which is a beautiful skin soother.
Get those rashes gone, get the pain gone, feel confident about your body and how it works by providing what it needs to work all the ways you want it to!