Hello; I considered soft pedaling my comments but chose to be blunt. The issue, to me, is the needless ongoing suffering of this fish in particular and that these situations will happen to most all fish keepers.I understand that the op is young and is making questionable decisions. but are these comments helpful? you both have the maturity and depth of knowledge to help the op in a more meaningful way.
This is an "ole yeller" type moment. Time of the suffering being a main consideration, at least to me. That the OP was putting off the needed action because it is an unpleasant chore seemed to be the case. My choice between having the fish continue in the miserable condition it was clearly in or be blunt to the OP was for the ending of the suffering of the fish.
To put it another way "mercy" killing of suffering pets with no hope of recovery is an aspect of this hobby we each have to make a choice about no matter the age.