360 total care?

Hi all, my 4 1/2 Month old was in similac advance rtf but then I couldn’t find it.Pedi said it was ok to switch to the 360 total care bc they are “essentially the same”. I had the 32 oz bottles and noticed baby was pooping a bit more than usual but I wasn’t really concerned. Then I couldn’t find the 32 oz bottles anymore so I picked up a bunch of the 8 oz bottles. For some reason it seems these cause my baby to poop literally after every bottle. She would even fart and poop would come out. She developed a rash from all the pooping and It was awful. I had some advance powder on hand so I have been giving that to her since yesterday and her pooping has improved it just a different color now. (Yellow)

Has this happened to anyone else’s baby? 😭I hate this formula shortage.