I've had a dark brown area under my toe nail (which i was assuming was blood) for 3 months now no improvement. takes up half toe nail. treatment?

The treatment: Depends on the diagnosis. Is it dried blood? Fungus? Bacteria? Melanoma? If you don't know then you need to see someone that does. Dried blood is no big deal but something like a melanoma is....

Not Toe-late Yet.: Unfortunately, there is no way to render an effective treatment without knowing what the cause of the brown is. As you may already know, it can be only one off several different things. It is either blood, bacteria, fungus, dirt or a type of melanoma. Now that you know the options, you need to be examined. With the possibility of melanoma on the list, I would not delay the examination too long.