Almost 11 weeks... diarrhea!

So my little guy will be 11 weeks on Wednesday. For about 6-7 weeks his poop regulated to twice per day. Once in the AM... once at night. For the passed three days he literally has poop in every single diaper. They’re not huge blow outs, sometimes it’s only the size of a quarter or a dime of wetness, he still has his two big poops but I’m noticing him pushing every 1/2 hour to an hour and sure enough there’s some sort of poop happening. It’s so bad that he’s now got a rash that’s starting to bleed a bit. I am now changing him every single hour plus anytime I remotely hear him pushing, plus desitin for protection. rash seems a bit better but the pooping isn’t stopping... he has no fever, sleeping good, no fussiness, no signs of dehydration at all, still had loads and loads of pee wet diapers .. what could be causing this diarrheaaaa!!!! Anyone else go through this? I’ll be phoning the pediatrician in the AM. Any thoughts or experiences appreciated!!