TMI :(

Yesterday evening I started having horrible stomach pain, and soon after that pretty bad diarrhea. Once I got home, the last time I went that night was really bad and dark orange and yellow (gross I know). I work up this morning still feeling really lethargic and crampy but no diarrhea. Until about two hours ago it started again :( it is still very yellow and foul smelling, and is very painful to me. I feel so sick and really haven't had an appetite enough to eat all day. I've been drinking as much water as I can but I still feel so gross. No pepto or Imodium has helped. Any idea what this could be/what I can take? I'm really debating if I should go to the ER tonight if it keeps happening. :(