I've started lifting like a month and a half ago but about a week ago my mid back and sometimes my lower has a mild pain. It usually hurts when i straighten my back in a sitting position. My lower back feels fine but when i touch my left hip i can feel the pain. I can walk fine and my lower back doesnt hurt. I'm 19 and never experienced back problems. - List item
When doing weight lifting exercises, you must also include core exercises in your routine to prevent back problems. Of course, this is in addition of making sure you do the weightlifting in an appropriate way. It's best to let experts monitor you in a gym until you have enough experience to do it all by yourself. And all this applies to someone who hasn't got back problems to begin with. In your case, your back problems requires some evaluation by an expert, if only to make sure you can continue to exercise.