3rd trimester.. have any of you experienced this?

Get checked. The mucus plug can fall out too early you need to make sure nothing is wrong. You may also have a bacterial infection causing the discharge. Your ob/gyn should have an on call number where you can get ahold of a doctor 24/7 to ask if you need to be seen asap or if it is something that can wait till your next visit. When in doubt go to the ER. It is better to go for nothing and feel silly than to not go and have it turn out to be something big.