Pain in the colon is a very generic symptom and could be a million different things, but is most likely due to the constipation. If I didn't poop for a month, I'm sure I'd be in pain.
The bottom line is we can't diagnose anything from the internet, only a doctor can. It's unlikely that it's cancer, so don't jump to the worst-case-scenario.
Stephanie, 29 years old
March 2000-Diagnosed Crohn's Colitis
(Tried every drug imaginable, but lived 10 years with daily diarrhea)
March 18, 2010-Total Proctocolectomy and Permanent Ileostomy! :)
(Now med free, 4 subsequent procedures to correct blockages at stoma site)
Stoma named Zoe...She's my best bud!! :)