Toenails are also susceptible to fungal infections. This is also known as onychomycosis or paranoychia. This disorder does not make you uncomfortable at all but it does cause discoloration, crumbling, and thickness of the toenails. So, basically, it can be quite alarming because it seems that you are being eaten alive. This fungal infection could be acquired from public baths, swimming pools, and gyms. You could also get it if you share footwear all the time or if you always wear tight shoes. Toenail fungus could also be brought about by a significant weakening of your immune system, inefficient drying of the feet, and an abnormal pH level.