Toddler Bowel movements

I'm worried. my toddler has been pooing more than normal since last Friday. I didn't acknowledge it until Monday when he went to nursery. He had a poo before he went and I send him with 2 pull-ups and he came home with the nursery nappy on. After that, he pooed twice again and also in the night. I started to monitor him and he's been going 4-5x a day. On Monday it had a strong medicated smell but has now calmed down. It's still smelly but not like his usual smell. His bum is also sore from all the pooing. The texture looks like undigested food, it's in normal colour, with no blood or mucus in it just mushy. I request a call from the doctors... still awaiting it. I'm really worried about what it could be. He's not been in any pain just a sore bum from all the pooing. Has anyone had this with their toddler or know what it could be?.