I'm starting to feel really bad. my mattress isn't good and I always sleep bad because my back will…

I'm starting to feel really bad. my mattress isn't good and I always sleep bad because my back will start to hurt and I'll have back pain all day but ever since I've been pregnant I've been sleeping on the couch more and more because it's the only thing that seems to help my back at night. my husband keeps asking me to sleep in bed with him and I tell him I can't or I'll lay down next to him until he falls asleep and then come to the couch. I was telling my mom the guilt I was having about all this today and she told me she would buy me and my husband a new mattress as a joint birthday gift. I about cried because it's not something she has to do but is doing it because she said not having a good mattress and having back pain is not s good quality of life to have.