Hi love! Please try to reach your OB kahit ngayon na, even a quick call or text, kasi back pain in pregnancy needs proper checking para sure na okay lang. A few of us moms have used warm compress during pregnancy, but it's really best to ask your doctor first kung safe for your specific situation, especially since you're having pain. Don't wait until next week if it's getting worse, okay? Your health and baby's health come first, so message your OB or go to the nearest clinic if kailangan. Take care!