Hello. I have pain in my lower back for about 3 days, sometimes an hou…

Hello. I have pain in my lower back for about 3 days, sometimes an hour in the morning. Today it started again in the evening. My belly sometimes feels hard but not painful. The baby's head is pressing directly into the vagina (I feel it). The baby is active. Also, there is a pelvic floor muscle tension. What could this be?