What Causes Abdominal Pain And Feeling Of Pressure In Bladder?

For the past three weeks or so I have had extreme bloating in the stomach, feeling like my bladder is never empty, weight gain of about 8 pounds and sharp abdominal pains that last about 5-10 seconds. I have had regular periods and I am not on the birth control pill. I took a pregnancy test just to be sure and it came back negative. I didn't really have any signs of pregnancy but thought I should rule that out. It does not burn when I urinate or any pain for that matter so I don't think it is a bladder infection. Bowl movements have also been normal. I had a blood and urine test today but I won't get the results back for at least a couple of days. I am just worried it might be something more serious and not sure if I should wait this long.