Clavaseptin and diarrhea.

My puppy recently had to spend a night at the vet, we are pretty sure he just ate something he wasn't suppose to, we think some type of plant. He spent the whole night throwing up and moving around like he had an upset/sore tummy, he then became dehydrated and lethargic so we took him to the vet who kept him for the night. They gave him an IV and got him hydrated. The vomitting had actually stopped before we took him to the vet, and he didn't have any diarrhea before the vet or during his stay with the vet. His temperature was normal the entire time as well. They still haven't really confirmed what happened, but the next morning they said we could pick him up, he was full of energy once again and has been ever since. They gave him Medi Cal gastro food, and 2 medications: Clavaseptin and Famotidine. He has been on this food and drugs for 4 days now and he now has diarrhea, the first couple days it was half sold stool and half diarrhea, but now it's just diarrhea. From what I could find both drugs can potentially give him diarrhea. Is this more than likely what is causing it? He still plays a lot all day long, and eats and drinks plenty, he seems perfectly fine other than the diarrhea. We also have his first shots booked for next week, only 6 days away (he will be 8 weeks next week). Is it still safe to get his shots? I am almost positive it is just the pills giving him diarrhea but will the shots do any harm to him while he is on these pills or perhaps his body is slightly run down because of the diarrhea so would the shots be safe?? The Famotidine medicine will be finished by tomorrow, but the clavaseptin doesn't run out for another 6 or so days, right when he is suppose to get his first shots... should I postpone his first shots for a few days? If it is the drugs giving him diarrhea should he stay on them or should he be taking something else? I don't want him to get dehydrated but he is still drinking a normal & healthy amount of water daily. Would giving him a pro-biotic or organic natural plain yogurt help give him back some healthy bacteria?
Sorry this is so long... I just wanted to be thorough! Thank you so much for your time!!

Sincerely,
Shanda Buchanan