*TMI description* Is this serious?

Please don't judge because I have no control over this, but I have really bad constipation problems. My doctor prescribed me a laxative, and it's working, but I feel awful. I've been going to the bathroom, but my lower left abdomen hurts real bad. I wipe really good after using the bathroom, and I do it the right way. I never wipe back to front, but after I poop and I wipe my butt, there is light brown stuff on the new toilet paper when I wipe my vagina because I peed too. When I only pee, there is nothing. I don't know what to do.