Abdominol pain and back pain the same time,starts at the same time every night

HI

I have abdominol pain right around belly button or a little below and middle back pain over a week now starts around the same time seems back pain may start first after 12 and one every night need to sit up the rest of the night  to relieve abdominol pain and back pain, during day hardly have abdominol pain but sometimes a little back pain, was hard to go to the bathroom a few days thought the reason of my problem was a blockage but took the magnessium ?? forgot what its called and that worked but that night the pain came on again around the same time,was wondering why this happens at about the same time every night

Thanks