I'd ask the doctor about icy hot or products like it honestly but try the heating pad on low nd see if that works or if you need pain reliever you can take Tylenol
I found using a heating pad on my back worked wonders!
I am 32w4d and my lower back is sore most of the time. According to my doctor, light rubbing/ massages are fine. I get my husband to massage the sore spots using lotion or baby oil before bedtime and I feel much better when I wake up. Hope that helps. :)