As of today, the larger mark by the dorsal seems to be the same, but the cloudiness toward the rear is gone. Still keeping a daily paraguard dosage and changing water every 3 days. Thanks for asking.
White cloudy marks disappeared after turning a bit dark. They are gone now. I think that it was most likely heater burn - but will never know for sure.
Not unless there is a problem in a tank. If there is a plec in a tank I don't go any higher than 1 TBS salt per 10G. This plec has not seen salt since I've him and I've had him less than a month.