Persistant diarrhea

My 20 month old boy had diarrhea with fever he was on antibiotics, the fever was gone but the diarrhea remained fast forward one week later he has another fever his stool is a bit consistant but not firm( i don't have better words to describe it) the ped gave him another antibiotics wich made his diarrhea worse but made the fever better. I don't know what to give him to make the diarrhea go. I am scared and tired . Please help. He is teething pretty bad his upper canines are coming. Has this happened with your babie how did you treat it. Thank you.