I am going to give you my best guess here as this gets into more medical information to give you a for sure reason why this is happening and I don't have the ability to do such detailed medical assessments.

My guess would be that after taking out your IUD ( I assume thats what you mean by your loop ) your hormones are fluctuating . your ovulation and preparation for getting pregnant again is what your body is getting used to. I would imagine that this sudden leaking will go away on its own as your hormones balance again. It isn't anything you should worry about  unless you start having an over abundance of milk and are sure you aren't pregnant. the test might be negative now, but if you miss your period you might test again...

my guess is, its really just your hormones trying to balance themselves. :) Best of luck getting pregnant again :)