It sounds like IBS
I notice a lot of members have it but you can have IBS or IBD without having Fibromyalgia
If you take magnesium supplements they can definitely cause it if your diet s already high in magnesium as well but most people don't have enough in their diet

I used to, it went on for years, i'd had endoscope, ultra sounds, all ok, it was caused by a lot of stress, anyway 4 years latter after going up to 10 times a day I had no control it was like a (tap) faucet running.then it changed and smelled so bad I wanted to vomit when I told my gastrointestinal she knew what it was and I had to do a frozen faecal test and the results came back and I was diagnosed with EPI basically my pancreious wasn't producing enzymes so I have to take enzymes every time I eat and I use gastro stop every 2 day., this is for the rest of my life, lucky it still supplies insulin.. And Im also using the fodmap diet but its jut trying different foods and see how they effect you.

I have the same problem and it's IBS . Seems to go hand in hand with fibro but mine's pretty much under control now using fiber suppliments (I know that sounds counterproductive but it bulks up the stool by soaking up the fluid) and watching out for trigger foods. I ended up doing a food diary to find out which things set me off.

I have found that metamucil has really helped me. Also less dairy, and sugar have helped me also.

Take a fiber supplement and it will regulate your stools pretty fast. I hope it helps. Hugs