Taking Probiotics For Gas And Bloating In Abdomen With Change In Color Of Stool. Are They Symptoms Of IBS?

I have started taking probiotics for 2 weeks now, because i passed gas and bloating all the time and a discomfort in my right abdomen, sometime lower and sometimes upper. At first i suspected gallbladder stones but i get lower abdomen discomfort too. (not painful just discomfort). Then i get green stool, sometimes a mixed of really dark brown and light brown, sometimes it's just dark brown, one day it was pale, the other day it was orangy. Now after 2 weeks of taking probiotics i noticed it's loose dark stool almost black, with a shade of very dark green. Should i be concerned now and have it checked? Does changed in stool color and consistency symptom of IBS? I heard IBS have abdominal pain cramps, i dont get one.