Hi... Please don t worry about sacralisation...as it is there from the time you born...so relax... Coming to your pain... I would recommend you to Keep icing your back frequently...to reduce spasm... To do lot of core muscle strengthening workout... To do glute stability to improve spine stability... To stretch your hip flexors and gluteus to reduce forces pulling on spine... Avoid lifting weights for a while..if happen to lift keep your back straight and bend your knees to lift weights .. Do spinal extensions frequently to avoid imbalance to set in.... Hope this is helpful for you.. Kindly revert back in case you need any further help in this regard..