How old are you? And where exactly is your pain located?
If it is on the lower right side of your belly seek medical help immediatly as it may be appendicitis.
Did you lift anything heavy recently? Is your pain located in your belly button? Or at your groin? If so Seek medical help immediatly as it may be hernia.
If your pain is located on the sides of your lower abdomen and are worst during periods and when you push the area you feel like an almond sized stiff area, then it might be an oviolation pain, if it is extreme then you may have cysts around your ovaries causing the pressure and pain. Do you have any unusual vaginal discharge?
Please give us more detail about your problem so we can give you a better help.
Where is the.pressure.at?