diarrhea

Question
My 10 month old lab had diarrhea and was diagnosed w coccidia. She was placed on antibiotic and has had 2 neg stool samples since. She is still having diarrhea, my husband believes that it is her food. I got the food from a breeder and realized after I began feeding it to her the best use date ( by a couple of months) had expired. I think the food was stored in a shed over the summer, but I don't know for how long. For a few days the vet had her on hamburg and rice and then I began to introduce the new dry food slowly. They have run blood work and did fecal floatation on her stool sample, but should they be running a more extensive fecal exam? Any help or suggestions appreciated. Thanks

Answer
Did she firm up on the hamburger and rice?  If so, likely what you switched to isn't right either.
Perhaps what you need to do is a longer course of hamburger and rice, a week or more.  If she doesn't firm up, likely it is some sort of a parasite and she needs to get back to the vet.  Sometimes they are hard to identify and cure.  Sometimes you even have to try a different vet.  

If she does firm up, slowly introduce a dry kibble over a week.  If she again has diarrhea, go back to the hamburger and rice again.  Then try a kibble with different ingredients.