For 3 Years Now I've Been Having Diarrhea 1-4xs A

For 3 years now I've been having diarrhea 1-4xs a week and it's always preceded by excruciating pain on the left side of my abdomen and above my hip, nausea,and profuse sweating. The diarrhea is either thick and very dark or loose and has what looks like white mucus in it. I'm at my wits end I have no idea what's wrong with me can you help?