Ok! So I hope to help connect some potential dots for all of you in this thread!
I too have been experiencing this for roughly the past seven years, given I'm only 25, it has still been a long time issue that has followed me everywhere I go. It usually comes with a belly cramp, sudden pinching, and something emptying that is definitely NOT my bladder.
Ok so heres the thing... warning for some Tmi that might be helpful. I have had this special talent in bed that has also produced an unknown liquid. I've always been able to squirt on demand, and I can assure you it isn't pee, it has always been clear with no smells and the feeling of pissing is totally different from this, it's almost like you are flexing your pelvic floor to get it out rather than your bladder. The problem is that doctors don't really agree on whether or not women squirt, and if they do they don't know what exactly the liquid is.
Well tonight I was getting freaking and I almost accidentally made a mess of my bed, I was able to stop myself but then an hour later.... a liter's worth of liquid came down my leg while I was in the kitchen. So it's like my body was still waiting to squirt (I hate that term for it lol)
There also seems to be a correlation when ever I do any floor exercises that involve my core. The harder I flex while working out, the more likely I am to have this problem later!
So I'm going to bet my money that this liquid is the same liquid that is involved in squirting, and that women always produce it but do not always excrete it when necessary and instead at random times.
I just wish doctors would actually try to research further into how women's bodies function during sex so I don't have to sound like a crazy person lolol!!
You can totally disagree, but considering my doctor won't give me other answers this is just what I tell myself!