Baby diarrhea

So my son is 9 months. He’ll be 10 Monday’s onNovember 1. Sunday night he started with diarrhea and it’s currently Wednesday and he still has it :/ my poor baby. He doesn’t seem in pain, he’s still active and playing but just not as happy as he was. Also I’ve noticed he won’t take my breast milk. I breast pump and I’ve noticed it’s harder to feed him he cries and refuses the bottle it takes awhile for him to eat. I’m a first time mom please anyone that can help? Has this happened to your babies?

Btw we made an appointment for him but it’s it till tomorrow 😭