Cm is thick and egg white to nourish the sperm and help it become the state it needs to be for fertilization. Once the egg is released, the cm thins out to a watery state and makes little "channels" for the sperm to swim up. The uterus also makes tiny contactions to help propel the sperm forward to meet the egg. It only takes about an hr from that point for the swimmers to get there. Since you just had a trigger, it could have sent your body a false signal and caused it to do it even if the egg wasn't released yet.
Hey, I don't know much about trigger shots and all, but I have herd that watery cm is fertile and usually comes before ewcm. Good luck!!!! I'm praying for ya!!!!!!!!