It can be relapse of IBS. Any stress, event, diet change, new drug...recently? It is characteristic for IBS: pain trigered by meal, and relieved by having bowel movement, switching between diarrhea/constipation, no blood in the stool, no major change in stool color, no weight loss.
What do you think?
Did your doctor check your kidneys? I had similar pain and turned out to be a nasty kidney infection.