Digestive Issues: Stool Never Consistent

[Bubalox]

So I have been under a lot of stress this year and after talking to my doctor, he thought I had a bit of constipation and told me to go on a pro-biotic. So now I poop everyday but the consistency is never the same, some days it's normal, other days it comes out loose or diarrhea, the other days it comes out thinner than normal. It just seems to be a cycle of randomness. My question is could this be diet related or what are the chances of underlying issues?

[purple1234567]

I would start with keeping a journal of what you are eating and if you are seeing any issues- you may be able to establish some patterns and better tell if it's diet or something else.