Any suggest to stop a grazer from, well grazing??

I'm seeking some help with one of my dogs who eats everything in front of her.

A couple of months ago, both my dogs got sick. I'm not sure how they contracted a virus, but I had the delightful experience of two weeks of doggy diarehha and vomit, before the medicine the vet prescriped did the trick.

During this time, I got rid of all the food and started fresh with everything, food supplements, everything and sanitized all their dishes and belongings. However, India continued to have a problem with very soft stool (I'll never eat soft serve ice cream again!).

Now, India has always been a grazer (i.e. she'll eat anything in sight). I mean it, she's eaten dates off palm trees, the seeds from the same trees, almost anything on the ground, even in some instances cat poop. I even had to give her a Heimlick manuver when she ate a brownie BEFORE I could stop her. Needless to say, she didn't like that, but the brownie came back up. When I'm out with them, I keep watch for items around us that may be a problem for them, food, trash, cats, traffic, etc.

My issue is (and I hope one of you has a viable solution) that short of putting a muzzle on her, what can I do to stop her from doing this? She's a very friendly and sweet natured dog and loves to say hi to people. I just don't want her getting sick again.

Any opinions, suggestions or assistance would be appreciated.