Hello! My son is 4 months old and has diarrhea about 10 times a day. W…

Hello! My son is 4 months old and has diarrhea about 10 times a day. We have loose stools. We've seen a doctor, he prescribed Regidron, Smecta, Furazolidone, Bifidumbacterin. Regidron couldn't give us 500ml a day. There's no fever. The diaper area turned red from diarrhea. We apply Bepanthen or Kizoil cream but it doesn't help. He immediately starts having diarrhea after eating. I don't know what to do anymore? Has anyone ever experienced this? Sorry, I'm adding photos of his stool.