Swollen/Bloated Axylotl (Another one, sorry!)

Sorry to start another bloated/swollen axolotl post, but I didn't want it to get lost.

My younger brother has had a brown axolotl, Rosie (not actually 100% sure of its sex) for 4 years. She has a tank to herself with a filter, a couple of plants and no gravel and has always been perfectly healthy. She's been missing a foot since we got her but it's slowly re-growing.
We feed her a variety of things but she's currently eating cockles. The tank is regularly cleaned although we never change all the water, always leave the new water standing etc

We recently moved her tank (still in the same room, just a different position) and the other day she was lying on her back, not moving. We thought she was dead so we went to fish her out and discovered she wasn't dead. Since then she's lying the right way up but is swollen up all over, including her head. She was eating but seems to have stopped.

After reading the other bloated axolotl posts on her we've moved her into a smaller tank with the same water, the filter and have put her into an unheated back room- we can't put her in the fridge at the moment but it is pretty cold in there.

Does anybody know what might be wrong with her?

She's never been ill in all the time we've had her and we're wondering if it could be because of moving the tank?

Any help would be greatly appreciated- we were really upset when we thought she'd died but she's not very healthy looking and we don't want her to actually die this time!

Thanks.

what temperature is the tank water that she normally sits in?

Was there anything that you added either to the water, tank (ie tank companions) or change of diet that might have effected her (apart from moving the tank).

Nothing at all has changed other than position, although we did catch the cat drinking from the water once. He hasn't got to Rosie or anything and we've made sure he can't do it anymore.

Not exactly sure on temperature- will try and find out. Just normal room temperature (UK) although it's an old house so it's not toasty or anything.

Thanks again.

do you have a thermometer for their tanks, if not might just pay to get one, especially when you start to head into summer again, to be on safe side.

I'd say if its in the UK and how the weathers been its well within the recommended temp, though that's without taking central heating into account...

Can't seem to get hold of a thermometer easily (small village- you know how it goes) but we're working on it. Seeing as she's been there for so long though I don't think it's the temperature.

She's been in an unheated back room for a week now and there's still no change- she's not eating or anything.

Just found out that a neighbour looked after her over the summer and fed her every day despite our instructions. Obviously after this there was a lot of dead food in the tank when my parents returned but this was cleaned out and she hasn't shown any signs of anything abnormal until now and it's a good 4 months or so since then. Could something like that take so long to affect her?