Help possible parasite!

Right I need help!
I have a group of 4 Chinese painted quail (3 hens 1 cock).
I have just taken away 20 eggs as they stopped sitting and started scattering around the aviary. As routine I candled the eggs to see if they were fertile (more than half were) but all were healthy ordinary eggs except 1!
This egg looks to be infertile BUT somebody else's eggs are inside it!! I would take a picture but my best candeling torch is my phone... Sorry! Will try to get one tho!
So the egg is almost completely clear apart from what looks like a bunch of clear eggs all stuck together. I have no idea what this is and have tried to research online with nothing coming up! I'm thinking a type of worm as I have a problem with slugs entering the aviary at night and I know these carry worms for dogs to imagine it's the same for birds. If anyone has seen this before please let me know what you know about this. Also I am in the uk if you have any advise on good parasite products I would appreciate it!
Forgot to say I will be cracking the egg to see what's inside so I will post a picture of that if they are visible without candeling. Thanks for any help!!

 

I've managed to take a picture!! The eggs float around inside the egg as when I move the egg they follow! Sorry it's not very clear but it's the best I could do

 

Ok false alarm upon cracking the egg all that was unusual inside was a group of air bubbles! So I researched that and found a picture similar to mine and it's basically a ruptured air sac so guessing that was just a bad egg! Now my panic is over but I guess I've given any other newbies an insight if this ever happens to them

 

Thank you I'm new to this site I've read many forums on here but only just registered still trying to work it all lol