How to pin down cause of diarrhea

[LilF]

Blossom has had some diarrhea the past couple weeks, loose wet stool/diarrhea. How do I know what could be the offender in terms of food. Diarrhea right after eating or diarrhea the next day. I put her on Vital Essentials turkey and beef along with gently cooked Open Farm which she is used to along with some home cooked steak or other additions that she is used to. The new Vital Essentials I have used for a month or so. If it did not agree with her how soon would I see GI issues? I am on my second bag of each--turkey and beef. Also, the Open Farm gently cooked consistency has changed greatly---more moist now and falls apart if you warm it up. It is like soup if you add broth to it. I understand they did not change the formula, only the moisture content. Could a lot of moist food cause diarrhea. I have given her Clay--RxVitamins (gave it to her last night and it always worked for my dogs but this morning she had squirting diarrhea after breakfast). I gave her pumpkin and some fiber over the past few days. Does eating too much food cause diarrhea. Her stool test I assume (I brought in a formed stool yesterday) was normal (they don't call if it is normal I guess) When she was eating Steve's raw she was doing fine but she was on the Vital Essentials and this new Open Farm for about a month now. I was also giving the Adored Beast Fidos Flora. Should I give the Proviable and more clay (I have not given her the dose for her age because in all my past dogs just a scoop or two worked)Maybe I should go back to Steve's food and stop the Vital Essentials and the Open Farm which is now too moist? One last thing she drinks about 2 cups of goat milk would that cause it? She has always had a good deal of that because she does not drink water. Any thoughts on what I described? Thanks