Can Aloe Vera Cause Dark Stools While Suffering From IBS?

I suffer with IBS I started taking 1x 135mg mebeverine every morning and 1x135mg mebeverine at bedtimne to try and stop the IBS manifesting on the weekends, I also started taking aloe vera tablets at the same time, about 4 weeks ago. In the last 4 weeks (twice watching the rugby) I had 3 double honey bourbon and cokes. I was not drunk and fine at the time but both times I much later got up in the night and vomited once and was fine after (this is unlike me, I always held my drink well although don t drink a fraction of what I used to). The night of the second vomiting, I passed a very dark almost black stool, consistency of porridge (wasn t foul smelling). My stomach has an ache low down and my lower back ache has worsened these last 2 months. Can aloe vera clear you out and make your stools very dark? Am I taking too much mebeverine causing constipation (Only been once since Saturday night and although same porridge consistency and quite watery, was a yellowy browny green? Should I be worried?