4month old having diarrhoea for 2weeks

Hi Mommies, My 4-month old son has been having diarrhoea for the past 2 weeks. Though not all poops are watery, he poops about 6 times a day (which was what led to me thinking that he's having a diarrhoea.) Been to the paedi 3 times and sent stool for testing and all turned out well. He's on probiotics - Biogaia even before this episode of diarrhoea. Formula wise we are using Similac Total Comfort which is already lactose free and very gentle on the stomach. He's still active, eating and sleeping well. No signs of dehydration. Only concern is really just the frequency and texture of poop. He poops so much that his butt is already quite sore. Any of you have experienced this? Can you please share if there's anything else I can do? Or is this going to be the new norm because doctor told me so long he's still active & stool test didn't show anything alarming, it shouldn't be too worrying. I've attached images of his poop.