Of course you should be worried.  Anything that makes you feel discomfort and concearned means "go get it checked".  Maybe you are reluctant to go because you are a guy (I don't know how old) and probably not medical savvy.  In my experiences in the health care field,  the doctor will do CBC (complete blood counts),  urinalysis,  and I hate to say it,  that dreaded  digital rectal exam to check for colorectal problems, urinary tract problems,  hernias, and/or prostate problems.  Those are the options.  You can do it when you finally get laid-out in the ER with complications and extensive diagnostic procedures done to you,  you don't know what hit you until the bill comes.  Or you can controll it yourself and decide what's best for you at your own pace.  Remember, if you don't want to get humiliated in the ER because you waited too long,  get checked out now and relieve yourself.

Just to be aware,  the doctor might recommend you get ultrasound test of your abdomen, pelvic area, perineal (between your anus and your scrotum),  sometimes the Dr. might order for a transrectal ultrasound test, too.  The other test would be a an anoscopy examination (an analscope put in your anus to view the whole anus), sigmoidoscopy examination (a longer scope to examin the entire rectum and where the colon starts), a colonoscopy (a scope that examins the entire colon). 

It's acrying shame that everything down there is all related to the ars.

Good luck.  Let me know how it went and if you live in Long Island, New York,  you have someone here to accompany you if you need help.  I've had Colitis in my past and on and off flare-ups.  I know what each and everyone of those procedures mentioned above and how to prep for them and so on if you need any info about it.