Suggest Remedy For Pain On The Left Side

about 6 months ago a pain on my left side started it comes sometimes between my hip & left ribcage then sometimes it will be in the back in the same place comes on strong, then stays like a nagging pain. had ct scan on kidneys came back fine, sometimes when it the pain is real bad i have to run to the bathroom. my family doctor put me on a new acid reflux medicine to see if it would help but it hasnt. ive also noticed the past few months my montly has changed. what could it be?