Pelvic floor dysfunction. Strain less.

When I go for pooping my muscles get contracted which makes me difficult to poop....i have to relax myself to poop...even a single thought create stress and leads to incomplete defecation... although my digestion is good....i think there is muscles are not cordinating well in my pelvic floor........i have a lower back pain also...i have to strain to poop.....i am suffering this from my childhood..in my childhood also i have suffered where....i use to hold poop and have uncontrollable bowel movement......i have to strain a lot in Indian style toilet and now since past few years i m using Western style toilet where i have convinced my mind....to relax so since it relaxes on Western commode i have to strain less ....but again a single thought of stress of not pooping leads to incomplete evacuation...