Chicken gaping when held and has clear watery droppings?

Hey all,

So I have a small flock of only four hens, three are 3 years old, and one is 1 year, the 3 year old hens were supposedly vaccinated, but I'm not sure against what.

Anyways, about 2 months ago one of the older hens started to gape when I held her under my arm. It was only when being held, and she seemed fine in every other way, so I took note of it, but didn't really worry about it. About a month ago she laid a strange egg which was misshapen and shell-less (http://i.imgur.com/OWUzRJP.jpg), and I don't believe that she's laid since. Now a couple of weeks ago, I noticed that she's been passing clear liquid out of her vent, I'm a bit confused, because she appears to be eating fine, but when you look at the dropping, it's mostly the clear liquid with very very little solid. There is no noticeable smell from the droppings either. Another thing is that she is a bit incontinent now. I used to be able to carry her without fear of her going to the bathroom on me, but recently, she'll pass the clear liquid on me...

As of now, I've tried to swab her mouth for gapeworm (she didn't like it, and I only got the inside of her mouth), and I gave her Epsom salt orally for 2 days because I thought it may be vent gleet.

Now I'm out of ideas, if anyone knows something about these symptoms, I'd be super happy to hear what it is.

Thanks!