I can feel what i believe is my descending colon when i palpate my llq. feels painful when full/fecal. no diarrhea or bloody stool. possible cause?

Constipation?: What you're describing seems like constipation, but a good history and physical would help matters. If you are chronically constipated you will likely need to cleanse out the impacted stool with a bowel prep that includes oral medications and possibly an enema, followed by a dietary eval and adjustment, based on the diagnosis. See a GI doc after seeing your GP and get some answers !

Get examined: You should not be able to feel your colon unless there is a mass. The most common mass, of course, is a large stool. Since you said you have pain when constipated, you should get that checked. Hope that helps.