What Causes Small Knots In Lower Abdomen And Passing Of Dark Stools?

ok,i have several small marble sized knots in my lower abdoman area down by my pubic area,also on my upper ribcage area and whn i eat both my left and right sides balloon out and is painfull. i have really dark stools several times a day. i get such sevear heart burn it feel like a heart attack. im just turning 40 this year,and female