Nursing is killing me physically

I am 28 but I feel like I am going on 98.. my knees hurt, my lower back hurts, I have Sacroiliac joint dysfunction, and shoulder pain from hoisting fat people up bed all the time .. I try to use good body mechanics and raise the bed + tilt the bed down to hoist, I try to use my legs and bend my knees whenever I am lifting heavy things etc .. but these morbidly obese people are killing me… they are dead weight in the bed and even with several people to help it just takes a toll .. I am trying to go to the gym to strengthen my abs, back, push/pull strength etc but it’s hard to go consistently when you’re in so much pain from work .. does anyone else have the same problem? what do you all do to mediate it ?