Lower back pain. Almost 6 months, plz

I'm having lower back pain. it has been almost 6 months. when I went for run, i was having some pain in my back, but i avoided it and went to run, and a fter that when I stretched my body, then suddenly pain was increased. after that I've shown it to a casual Dr in a government hospital. he gave me pain killers. but it didn't give me relief, so I searched on PRACTO and found a physiotherapist Dr ankur agarwal , koh e fiza, bhopal. he asked me for an X- ray (digital), I had shown him the x-ray, and he told me, all is well, spine curve is good. the pain in your lumbar spine is occurred because of your bad posture of sitting for long time. then he gave me diathermy shortwave tharapy for 7 days, after this tharapy I got relief from pain. after this tharapy he asked to do 6 exercise, like leg rise, and cobra pose. these exercise gave me better relief, I was thinking that it has just cured. and he told me that daily exercise even after you get cured, but I'm not cured till now.