Uncomfortable bed in early pregnancy

I'm only four weeks pregnant and the past few nights I wake up because the middle of my back hurts so bad it's hard to even move. Its probably way to early for this and I'm wondering if its because of our bed. I've already thought it was a little uncomfortable and hard. In the past. For a long time we had a memory foam topper but it got pretty old so we threw it out. Is there something I can do to make the bed feel better? Have you found that you prefer a firm or squishy mattress when you're pregnant?