What are Braxton Hicks contractions supposed to feel like? Before, my belly would just get hard for…

What are Braxton Hicks contractions supposed to feel like? Before, my belly would just get hard for 30 seconds and then relax. But now, when I lie down, they're painful: I can't even roll onto my back a little to relieve my belly because the pain shoots to my lower abdomen. It's much easier to bear them upright. Walking is hard – it feels like something is scratching inside my lower belly. At 34 weeks, my OB noted that the baby's head was already very low in my pelvis and advised me to walk less and lie down more for the best outcome. What did you experience before labor?