How long a dog can go with out passing stool varies
Is this the same pup that has been have some problems with loose stool?
How many days has it been since she last passed stool?
Did she every pass the rock that she ate a few days ago?
I am glad she did not eat the rock.
Deworming can cause mild diarrhea and or constipation in some dogs. Once day is not a real concern as long as there is no vomiting involved.
You can try adding 1 teaspoon of Metamucil or Benafiber if you have this at home this will help to pass stool.
If she goes more then 2 days without passing stool, stops eating or begins vomiting that would be cause for concern as this can indicate a blockage in the digestive tract.
As for the dog food yes you should switch to adult food at the age of 1. You want to switch slowly by adding the new food with the old. I suggest doing this over a period of 7-10 days to prevent digestive upset.
I hope this has been helpful, please let me know if you have any additional questions.
No it will not cause a problem there is no need to get rid of the puppy food. I would buy adult food when you have about 1/4 of the bag of puppy food left and slowly begin mixing them.
Yes dogs can digest gelatin.
The gelatin may not work as well as the metamucil or Benafiber. You can also use canned pumpkin if you have that.
If all you have is the Gelatin you can try it will not hurt but I would suggest the others if possible