Constant urge to poop, tenesmus?

YO, food poisoning 3 weeks ago, 3 days ago after a thin loose poop i got the feeling of incomplete evacuation, like my was still relaxed, and it hasnt gone away, i feel it all day and it is kinda painful at night, whats the deal? inflammatory bowel?? colitis? proctitis? 19 year old male no problems in family history, and abdominal discomfort and loose stools for 3 weeks but discomfort has decreased dramatically