Hi Carole,
Welcome to FishLore.

It could have been your water was out of whack, I don't know.
I agree with FishKing about getting a test kit, most here recommend the
API master test kit, it is very accurate. The strips are not.
Had you done anything differently a couple days prior to him getting ill?
It seems to me that since you've had him for a year with no problems, whatever your routine is, is working for you.
Water changes can be stressful, 20-30% weekly is recommended for a cycled tank. You can use a turkey baster to get rid of waste on the bottom.
Does your tank have a filter?
The goal is to allow beneficial bacteria to grown on the plants, decorations, gravel and in your filter.
The bacteria 'eats' the harmful ammonia from fish waste and left over food. So by cleaning and wiping everything down you could be wiping away the beneficial bacteria.
How is Eric doing today?.....Oh we love pics!