Without examination, I'm not sure what could be causing the pressure that could be related to the diuretic.
I would indeed be evaluated by a physician. Imaging tests should be done, including, a CT scan or ultrasound. These can exclude a mass or fluid within the abdomen.
If negative, a colonoscopy can be considered to evaluate for a problem within the GI tract that can lead to swelling and distension.
These options can be discussed with your personal physician.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin Pho, M.D.
KevinMD.com
Twitter.com/kevinmd