It sounds like the plug to me, but the plug coming away doesn't nec mean labour is going to start. Ring your midwife and inform her what has happened, but don't panic. The mucous of the plug is constantly being replenished and it may still be weeks untill something else happens. Take it a bit easier, maybe ring family members and ask them to help you for the day if you can. Keep up your fluids and just be aware that it MAY happen, or it may not. Be prepared IYKWIM for both circumstances. I'm sure ur little one will be in there a while longer honey