floating upside down and white coating

Well I had orandas for the last 15 years and it never gave me troubles until
the last months.
First I had the floating up side down and lost several fish, even with the
85 degrees water temperatur plus the epsom salt. Now, lately fish start
turning up side down and have bloodshot biiiiiiiiiiiig eyes with white
coating.
I am pretty much on the end of my knowledge what the heck is going on. The
water quality is fine, the food is flakes (to not get them to float again).
Every advice welcomed.
M.

No idea, but if you say the water quality is fine, I'd still
do regular water changes, to remove any impurities you cannot see.