TMI question: so I'm getting ready for shower then bed right well in my underwear there's like this…

TMI question: so I'm getting ready for shower then bed right well in my underwear there's like this milky looking stuff..... no smell, is this my mucus plug and how long does it keep coming out? it's been three days since I noticed it. and does this mean I could go into like actual contractions? I'm to set up a c section as soon as my Dr looks at her book. I don't know if I should call my high risk Dr and tell him about it aswell. it's the size of a thumb