Baby is sick

Hi guys! My baby is 6 months old and has had diarrhea since about Monday. And I mean bad doo doo all day long! But, no other symptoms! So, I took him to the doctors on Wednesday just in case. Well the doctor said it might've  been something he ate and his body rejected so she said he would be better within 24-48 hours. Well last night I noticed he was sleeping more and was VERY cranky. And now today he literally has been sleeping all day, not eating much, and very cranky and upset and still had diarrhea pretty bad. He's also had a small fever. I might have to say he's been up a total of two hours today and it's 7pm. And maybe drank a total of 6oz of milk. Doctor said no real food just water and formula. I took him to the doctors today and they gave him medication. What else could I do he doesn't seem any better. 😭 sorry for being so upset I'm a first time mom so I worry too much