Need answers !!

I went to obgyn today for a regular 30 week check up and they checked my cervix just to be safe because I told them I was having what felt like Charlie horses in my stomach often and long periods of time . When they checked me my cervix was open slightly in the outer part of the cervix while the inner part was still closed . I’m unsure what this means and if I should be worried I’ve lost a large piece of my mucus plug tonight and it’s happened Twice in the previous weeks . This is my third pregnancy and none of these things has happened before and I’m just trying hear anyone else’s experience with this and what this means .

P.s my doctor didn’t tell me much just rushed me out , didn’t answer really any questions .