I Have Had This Problem For Several Years. But, It's

I have had this problem for several years. But, it's getting worse. Problem with elimination of poo. I'm not constipated. Doesn't matter if it's loose stool or hard stool, feels like something is not opening/allowing poo to pass. Pain in the left sciatic area and numbing from left buttock cheek to back of left knee. I have seen several doctors over the years, GI specialists, tests and no solution. But, it's so getting worse. I feel very backed up. Any suggestions?