Aw mama, I totally understand your worry kasi iba talaga ang bawat pregnancy! A few of my mum friends also had cramping na mas intense sa second pregnancy compared sa first, pero 3 weeks straight na at grabi ang intensity, I'd really push to get a second opinion or at least ask your OB to do an ultrasound just to be extra sure, especially since it feels different from your first baby. Your instinct as a mom matters, so don't hesitate to call your doctor again or visit another OB if you're not fully reassured, better safe than sorry talaga, hindi ba?