Shrinking cervix?

Tricia
Just got back from dr, was having contractions 2-3 minutes apart. He checked me and I was 1-2cm and 20% thinned. Couple weeks ago I was 2cm 60% thinned... Happen to anyone else? This isn't my normal doctor and I don't like this guy very much but I'm so confused. He sent me home. 35 weeks.