I've been playing for almost a decade and I have recently been having problems with my left side when pulling down my front arm (left) to bowl (Both medium pace and off spin). If I pull down too hard with left arm I get a pain in my left lower back, just above my pelvis, which slowly goes away within a month, but no matter how long I wait, I keep getting the pain if I pull down too hard.

I can just not pull down as hard but that means a loss in my length control. Anyone know what is wrong and how to eradicate the pain?