Doctors think her skin isn't getting enough oxygen -- she is also lacking sufficient amounts of vitamins A, B, C, D and K, according to her mother.
But with treatment, she is improving.
"Her legs aren't covered in black scabs," said her mother. "They are looking better, and her face just looks like she has a real bad sunburn."
Today Isom is on 25 medications, but her insurance only pays for five of them. She is awaiting the results of genetic tests that may give doctors clues to what is wrong.
"The doctors are so caring," said Gary. "It's just amazing how much they have done for her. We really didn't think she was going to make it."
Isom said she slipped into a depression, but now feels uplifted by the support of family and friends.
"I know it's a blessing that I can reach out and touch people's hearts," she said.
She remembers the day at Johns Hopkins when she felt sorry for herself, shuffling through the corridors on a walker.
"I saw a little girl, 4 or 5 years old, and she was walking through the same hall and had the biggest smile on her face," said Isom. "She had braces from [her] hip to her feet and had a walker and held her head up so high. I thought, 'If she can, I can. I had a life. This baby is trying to have a life.' ... I fed off her energy."
Isom said she prayed, "I will never be selfish again."
Gary said their ordeal has been a "nightmare ... to see her whole body shut down."
But she gets her strength from her daughter.
"Shanyna is remarkable," said Gary. "She has been able to hold her head high. I keep telling her we are going to make it, through the grace of God."