It can also be caused by fungus.
https://en.wikipedia.org/wiki/Fin_rot
Although it's possible for there to be a concomitant bacterial infection in a fish with fungus, and the Ich-X would likely only have an effect on the fungus.
In the past when treating fungus, I have used Kordon Rid Ich Plus. I know it is marketed as being for parasites, such as ich, but it also works to treat fungus.