Toddler Diarrhea Stinks!

I'm going to complain today.  Fiona has had diarrhea since well before Thanksgiving.  It stinks ... literally.  It all started when we all got the stomach flu the week before Thanksgiving and has been going on pretty much nonstop.  I'm at my wits end.  It is not fun to have to change her clothes 2-3 times a day because of blow out diapers.  And I'm talking about blowing out of cloth diapers.  Don't even bring up disposables.  We tried switching to disposables at the beginning of all this because I didn't want to wash all those stinky diapers.  However, it was a major fail because a blow out in a cloth diaper is frustrating, but only minorly messy.  A blow out in a disposable requires a hazmat team.  So I've had to suck it up and wash all those stinky diapers.  We're talking 3-4 diapers a day, since Thanksgiving.  It has not been pleasant.
Aside from the general frustration with stinky diapers and wardrobe changes I was getting pretty concerned about her health.  We've tried just about everything to try to get rid of the diarrhea.  We've tried the BRAT diet, we've tried anything and everything that usually constipates kids with absolutely zero luck.  So I just try and really push fluids every day to make sure she doesn't get dehydrated.  We've been to the pediatrician multiple times.  We've actually switched pediatricians because the first wrote the whole thing off as teething and wouldn't take any of my concerns seriously.  After long hours on the Internet searching for answers and talking to a family friend who specializes in infant/toddler nutrition, I knew that probably what she had was called "toddler diarrhea".  However, since we do have some family history of celiac and crohn's and other food trouble I wanted to just have her tested.
Thankfully, the new pediatrician completely agreed with my concerns and we tortured my poor baby girl with blood samples and stool samples.  They tested for everything under the sun.  It was hard to wait to get all the results back.  My gut said they would be negative, but I still worried.  I imagined how much our life would have to change if she turned out to have celiac.  Anyway, all the tests came back negative.  It was a sigh of relief, yet still extremely frustrating.  I'm not saying I wanted the tests to come back positive, but it would have been an answer and we could have developed a plan from there.
The pediatrician deemed it "toddler diarrhea".  Basically chronic diarrhea, where the child still maintains a normal growth curve.  Thank God.  At least she is gaining weight and growing like she should.  However, since Fiona is on the lower end of the curve, we have to go in regularly and weigh her just to be sure that she keeps gaining. 
I'm just so frustrated and annoyed.  Toddler diarrhea usually occurs when kids drink too much juice or eat foods that have sorbitol in them.  Fiona has never gotten to drink juice.  I think it is just empty calories and we have never given it to her.  She also doesn't have any sorbitol in her diet.  We've tried every suggestion out there for toddler diarrhea.  However, it is challenging, because she does still have a sensitivity to dairy products.  We've tried high fiber diets, we've tried high fat diets, nothing works.  I'm trying to be patient and let it clear up on its own, but this can last until age 4.  Age 4?!?!  I think I will lose my mind if it lasts that long. 
Anyone go through something similar with their kids?  Is there a light at the end of the tunnel?