I am so sorry you have been going through such a rough time with this. Very scary to read through your thread not knowing what the real issue is. Knowing that she ate some of the dog bed was a concern. Reading about several blockages here on the board will put the fear of God in you!

It's always a concern of mine. I've never gone through it but knowing that it's fairly prevalent makes it a concern. I don't know if Dobermans are getting more attracted to non-food items somehow or if every breed goes through this. But I know as a puppy, Annie wanted to taste everything! I spent every waking moment watching and saying, no no, drop it, leave it! It just becomes a part of your life. Frustrating as hell sometime!

Like, why do you want to eat that!?

But my main concern was not letting to turn into a habit. She's getting better at ignoring a lot of different things but it still goes on. She's so young and still learning. And it's hard to watch them every second.
And that said, it seems there's been a lot of people on here over the years who have seem to have Dobermans that have sensitive tummies. I guess like people, some are allergic to certain things while others are not.
I do believe food plays a great role. And finding the right food for
your particular dog is important. Annie has been on Muenster food - Perfect Balance Chicken since bringing her home, as that is what her breeder feeds. (With toppers) She is always had a good BM, I will say.
I have Kali on this kibble:
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Its raw coated kibble and she also gets Stella and Chewy's Frozen raw patties and other toppers. And she is always done well on it. I've been giving Annie some of the raw patties for a while and recently I've been throwing a handful of Kali's kibble into Annie's Bowl hoping to transition her over so they can both be on the same thing. So far, so good. But if I have any problems with the switch I will be going back to the Muenster.
I still feed Annie 3 times a day.
Have you tried a bit of pumpkin when Pepper had the diarrhea? Can't remember if I read that or not. Thinking of you and hoping that things go back to normal for Pepper.