When I had my son my placenta was completely falling apart just very dead not much calcium just…

When I had my son my placenta was completely falling apart just very dead not much calcium just gross and also my sons umbilical cord seperated from my placenta when the nursing students were examining it soon after birth I had my son at 35 weeks and I started having contractions 30-40 seconds apart but was not dialating I'm now pregnant with number two and I am scared this will happen again and the doctors had no idea why and I had a ultrasound the week before and no one saw it please someone else have this I'm going to see a couple different obgyns to see if I can find one I like in my area and hopefully they will have some answers I'm praying someone else has had this