Hello everyone. Second pregnancy. This time I'm very worried about my …

Hello everyone. Second pregnancy. This time I'm very worried about my lower back. (I've never had it before) I walk with my son on my arms plus five months pregnant. Even if I just walk for a long time on my own, I can't straighten up afterwards. The pain is shooting and enclosed. Like it gets stuck all day. It only goes away when I sleep at night. Obviously, there's not much you can do with ointments and medications for pregnant women, but suddenly anyone who also suffered from their lower back and knows the answer to what to apply to make the pain go away?