Every rose has its thorns

If you have ever had the joy of eating a meal with my family and I, you know what a process it can become. The girls are and have always been wonderful eaters. They will at least try anything we put in front of them. And when they eat, they EAT. They are by no means "bird eaters". They can inhaled massive quantites of food that sometimes leaves me asking "where did you put all that?!?!" They are very tall and skinny.
Reese, on the other hand, is SUPER picky. That doesn't even scratch the surface. He is beyond picky. He will usually only eat fruit, with the occasional grilled cheese, bacon grits and a rare (as in time, not cooking) chicken nugget. I do only allow him fresh fruit as I feel that if he's gonna eat it, it might as well be the healthiest I can get.
Well, today we went to a good friend of ours' little boy's b-day party. They had those little smoked cocktail weenies with BBQ sauce. I fixed my plate and sat down to eat. I, as always, offered Reese a bite of a weenie. To my surprise, HE ATE IT!!!! And even said "Mmmmm" Which is his way of letting me know he REALLY likes it. I was elated. Ya'll he NEVER eats anything new I offer. So I continued to feed him several. I stopped only after I realized he had eaten A LOT and I didn't want to upset his sensitive stomach.
We went and played. He did his "poop thing" - its so dramatic, but hilarious. (I know this is TMI, but I"m trying to save this memory). Immediately, I knew something was wrong. He absolutely refused to sit down. This isnt completely abnormal since when he was an infant, we would rush to change his diaper because he had such stomach issues (we needed to check the poop - I know, I know, TMI). This resulted in a bit of a Divo - he hates to have a dirty diaper. Anyway - back to the story...
He would not sit down, so I decided to check his diaper. Sure enough, it was dirty. I laid him down and proceeded to "do the deed". When I took off his diaper, I gasped! Ya'll, his bottom was SO red. Bless his heart he started screaming and continued to do so while I gingerly wiped him off. IT.LOOKS.HORRIBLE!!!! I caked on the Desitin and diapered him up. He laid on my shoulder the remainder of the party. He's pitiful.
When we got home, I let him run around naked, but everytime he sat down or fell down, he would cry. We did a bath and that seemed to help. But you can tell he's really uncomfortable. Bless his heart. I feel so bad.
I told Cory. His response "Sometimes the best things you will ever put in your mouth will literally tear up your behind coming out!" Love him! Does anyone have any tips on how to help my little boy recover any quicker?!?