I have felt some pressure below the belt line for about 3 days. If I press real deep it is painful. Last night I had sharp pains which kept me awake. I woke to have a bowl movememt but only gas came out and mucus with minor blood in the mucus. This started after my physical 2 days ago where the doctor perscribe and antibiotic for a sinus infection. Blood test was all within limites. I looked up the side effects of the antibotics and it said may cause colitis type symptoms. I m male and 63 and have had all required recent exams 1 year ago including cat scan of the lower abdomin and chest xray. Nothing found. I quit taking the medication but the pressure is still there but the stabbing pains are less since I took some advil. When I caugh that when I feel the pain the most. Ant ideas.