I have been diagnosed with ibs but i wonder if that's a correct diagnosis. i have continuous pain in my left abdominal back and stool with bad smell.

Have u been checked?: "stomach pain" can be caused by lots of things & may indeed originate outside the GI tract. Further evaluation is in order before anyone can answer "what to do" or diagnosis IBS. Your doctor will want to re-examine you as well as know the quality, timing, duration, location, & associations (eating, position, activity, stooling, urinating) of your pain to better direct the next appropriate testing.