I Can't Have A Bowel Movement Without Taking Miralax Every

I can't have a bowel movement without taking miralax every night. My stools are very runny soft piles and I never feel like I get through. I have been having some pain on the left side under my rib cage. Having lower back pain and lately sever pain in the abdomen, radiating around the left side and back. So sever one day I spend the whole day in bed, but finally got easy. Are bowel blockage sometimes hard to see in the small intestine?