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please help! Sick fish

Subject: please help! Sick fish
by SophieAnnxx on 31/5/2013 20:55:58

The tank is 64 litres and has two inhabitants, Internal filter for tanks 45-110 litre with carbon ( carbon is always removed when the tank is being treated)
Hi, I apologise in advance for this post being long. I have just got back from university for the summer and while I have been away my aunt has been looking after my goldfish, over the last few months they seem to have encountered many different problems and she has been given lots of different advice from many different pet shops.
My black Moore has had slime at least three times in the past two months and has been treated for it with medication, my aunt took a water sample into the fish shop and was told it was due to the presence of ammonia in the tank, the man then told her to do a 50% change every week to get the water quality back to normal, she did that and everything was fine.
However I got back from university yesterday to discover that my black more has white slime around her eyes (what I presume to be slime again) and I suspect my shubunkin has dropsy, he is very bloted and his scales are slightly raised (they look like they could be beginning to pine cone)
The tank water is also VERY clean so I was wondering if such large water changes every week could have messed up the nitrate cycle that that could be what is causing the high ammonia levels and the continuing illnesses? The tank was treated with ammonia remover a few weeks ago and I don't know whether to do it again. I don't have any testing strips but i am going into town tomorrow to get some and any treatment that is required.
my problem is I don't know how to treat them, I didnt want to do a water change just in case that's causing the ammonia problem? also how do i treat for dropsy and slime and also sort out the problem with the water! Please help I don't know what to do!