Two periods back to back after baby

I had my second baby four months ago. I got my first proper period it lasted a week and a half I had extremely painful cramps however was expecting this as it’s normal to have this after child birth. Two days later I started bleeding again heavy and I’ve got the worst stomach pains and feel sick.

I’ve tried to look online for advice but can’t find anything. Has anyone experienced this before. I’m not sure if this is normal or I should be checking this with a doctor.

(I never had this with my first after he was born)