Is this normal back pain?

I'm 30 weeks pregnant and about 4 hours ago, I took my trash out to the dumpster and 5 minutes later I started getting lower back pain. It's not constant back pain, though, and seems to pulsate. So basically anywhere 5 seconds to 10 minutes. I'll get a throbbing back pain feeling that lasts for a second or two. Sometimes the back pain is accompanied by pain in both my groin areas (which is my normal place for RLP, but paired with the back pain it's worrying me). Is this normal pregnancy back pain?