Early pregnancy

So I'm 4-5 weeks pregnant and I have morning sickness so bad. Except I don't get it in the morning. I get it either in the afternoon or at night. But I didn't think it was possible to get sick this early? And is it possible to get extreme lower back pains. My back just feels so stiff and the lower part hurts. Is there anything I can do to help with that?😩 this is my first pregnancy. So I'm definitely new to everything.