Unwell bubba?

My LO, almost 11 months old isn’t doing so great today, his stool is like a pale brown/nude like colour? He’s gone a few times today and one being sortve watery? His bum and around is very red and sore and is just crying so much 🥺. Is this teething? He’s never teethed like this before and he has five teeth. He has started transitioning to cows milk about two almost three weeks ago and I half it with water and he loves it otherwise when he’s not drinking that he is still breastfed as well. He hasn’t had issues with cows milk so I assume it wouldn’t be that given he’s only not well now? Is usually a very happy and healthy bubba but not today. Just thoughts and advice please 😊🌸