I'd hardly call those fins rotted, they're beat up and likely from the spawn, smallmouth spawn in water between 52-58 degrees, and Ahmic Lake should be between 58-62 right now. The fish should be on their beds now, some should be done their spawn.
That fish is otherwise healthy looking, the blotching wouldnt be causing it any harm. The blotching is often caused by skin pigment hormones that are associated with stress ie. catch and release, livewell holding, spawn, but is not necessarily relevant to the fish's current state of health as the markings will stay for life.
I hope this helps. Ahmic Lake seems to be especially bad for it, I've caught many smallies with blotching (although none as crazy as this one) I've caught the same fish off the same spot on two different years. Same mushroom shaped blotch on his cheek