Ive been watching the show "house" on tv
maybe you have multiple problems going on
stars, red bugs, flat worms are all invisible to you until you go through this kind of thing.
I would also suggest something that happened to me. I ran my tank at 80 degrees for years, I had a mysterious dyeoff this spring. I found out that my chiller said 78 it was really about 84. My back up thermomiter was off low and it said 79 when it was really 84. I can remember on a few hot days my chiller kicking on when it reached 82 on its thermostat so periods of the day my tank was getting to be 86 degrees Im guessing. That could cause some problems I would think.
just a thought
we are all pulling for you
josh