To put things in perspective, African lungfish in the wild can inhabit small ponds or pools that totally dry up for a portion of the year. At those times the lungfish burrows into the mud and secretes a slime that forms a thick covering around its body. It then enters a state of quasi-hybernation till the rains come back, at which time it wakes up, shakes the slime off, and goes about its business in the refilled pond/pool. The point is, at different times during its life cycle many wild African lungfish endure far worse living conditions than you are providing now, so, don't feel too bad!
http://en.wikipedia.org/wiki/File:PSM_V63_D037_Clod_of_earth_containing_cocoon_of_lung_fish.png
http://en.wikipedia.org/wiki/Community_aquarium
Now I'm not saying the OP should feel bad but I have to disagree about a drought being worse then living in a small tank and being covered in ammonia burns/fin rot or injuries. The lung has evolved to fairly comfortably ride out a dry season but isn't adapted to poor water parameters caused by being in too small and unfiltered a tank. The Lung is actually suffering in this case, enduring hardship it has not evolved to endure and I only say this so the OP doesn't get confused by your post and assume that the Lung is okay because of your implication that they endure worse naturally. The fact is they don't as they use the slime to protect their bodies and only really endure loss of food which their body compensates for which is a far cry from being physically injured by poor water quality or improper housing. So please don't under play the situation to make the OP feel better if anything just point out their mistake isn't uncommon and as long as they try to fix it they shouldn't beat themselves over it.
Everyone stumbles and falls but we don't learn to get up or not stumble again by denying it, we learn and grow strong by acknowledging it and taking ownership of our mistakes. To deny it is to ask history to repeat itself.
