Nail Health question

I have had this nail issue for 3, going on 4 years. When it first started it would keep splitting no matter how much I grew it out. I've been using press on nails to help it grow without splitting but I have been getting green discoloration due to the moisture under the press on nail. Starting from before the cuticle, the line has a white center with a darker border. Is my nail splitting at the bed? What can be done about this? Is it a fungus of some sort or vitamin deficiency? Willing to try anything, I've gone to two primary care docs about it and they didn't have an answer for me. Should I go to a dermatologist?