Mucinex side effects

LJ • Baby girl born Feb 19, 2015 and second girl born Jan 20, 2017. Baby #3 due in October!
Might be TMI but has anyone had diarrhea as a side effect from taking mucinex?  I started taking it yesterday and I've had to run to the bathroom five times today already. I'm hoping that maybe it's just a stomach bug or maybe from new cereal I had for breakfast. Only on CD 8.