Why after i go take a #2 do i feel like i still have to go but can't?

Unfortunately : While this is more common with #1, the only way to know is to perform an examination shortly after having bowel movement to confirm if the sensation is due to residual stool or a possible mass. You should discuss with your internist or a gastroenterologist.

Is this new or not?: The acuity (or not) of your complaint determines the urgency of your evaluation. You may have anal or rectal trauma, a large hemorrhoid or fissure causing hesitancy, pelvic floor dysfunction with altered rectal function, colonic inertia with slow transit, irritable bowel syndrome, procto-colitis (infectious, inflammatory, ischemic), extrinsic impression against gut, lots more. Go see your doctor.