Back pain

I'm only 5 weeks n 5 days and sometimes my back be killing me...I'll lay down for a little bit and it usually goes away but yesterday I had this constant back ache kinda like towards my butt that I couldn't shake but it stopped last night..and I just woke up and haven't done much now my back is hurting again. Is this normal? Isn't it to early to be having all this back pain? Anybody else having this?