Uncomfortable feeling & back pain, contractions?

My belly feels a little hard and uncomfortable and I have some back pain that doesn't go away even if I change positions (normally my sciatica pains get better when I lay on my back). The feeling has been consistent for about an hour now... Should I be worried or are these just braxton hicks? I've never had them before so I don't really know. 😕 I'm only 28 weeks pregnant so baby should still stay put for a few weeks. 🌸