LO is having diarrhea for 4 days

My 11mo LO is having a flu and already visited the PD on 11-Dec. he has been having diarrhea since we went home that day after having the meds. Today is day 4 and He is still having diarrhea, about 3-4 times a day. I also realize that there is a tooth popping out ytd. So I am not too sure what causes him to have diarrhea for straight 4 days (the flu, the meds or teething?) he also doesn’t really have good appetite. Appreciate any advice! TIA