Cramping. FTM and concerned

Athena

I’m 28w1d with our baby boy. A few weeks ago I had light vaginal bleeding but I went to the delivery room and got checked and they said all looked fine and my cervix wasn’t open or anything. I was having contractions but I couldn’t feel them. I’ve been trying to stay active by walking 2-3 miles a day (if I can) and I’ve been starting to cramp a lot easier now. Not even a mile in of a very slow moderate walk and I’m getting light cramps down by my lower abdomen. It’s getting harder and harder to bend or function and my back pain is becoming insane. I don’t know if I should be concerned or not.. just a little scared. His heartbeat was good at the last appointment but should I stop walking or doing activities? Even just doing laundry made me cramp up in my belly..