Hi L.,
You are experiencing the story of my life! We did end up going to a GI doc, who diagnosed my son with "non-specific toddler diarrhea." (In other words, couldn't figure out the cause!) The good news was, he ran some tests and ruled our many illnesses and diseases such as Chron's, parasite, and allergies.
Here are some things that have helped our guy:
-as the other ladies have said, BRAT diet
-add 1/4 cup baking soda to bath water to soothe the rash... we've also given our little one Aveeno oatmeal baths
-put Vaseline or Bag Balm on his bottom at every diaper change, even if there's no rash. Avoid creamy diaper creams like Desitin, because the cornstarch base may actually feed the rash, which can be a yeast infection when it gets really bad
-limit juice & cut back on servings of fruit, especially citrus
-wipe his bottom with a soft washcloth and warm water, no soap (daycare lady is sure to love that one!)
-dry his bottom w/a hair dryer if he'll let you
-give a fiber supplement. Our son was 14 months and about 20 pounds when we started this. We give him 1 Metamucil fiber wafer each morning. They taste good and seem to help bulk up the poops
-as another mom mentioned, we also give our kids acidophilus. I buy Nature's Blend chewable acidophilus tablets
-make sure the daycare provider knows how important it is to change the poopy diapers IMMEDIATELY. Our doc said having the poop in contact with the skin essentially burns the skin.
I hope this helps. I know how frustrated and worried you must be, and how much pain your little boy is in.
Good luck :)
-P.