Amanda Coveler, a woman who successfully gives birth to a second daughter after two miscarriages, faces challenges after giving birth.

Doctors can't pinpoint the cause of the array of debilitating ailments a woman has been suffering from for more than 50 years.

A baby boy has bouts of vomiting and diarrhea from the day of his birth; a young woman experiences blackouts after she hits puberty.

A man suffers from a series of debilitating symptoms; doctors cannot diagnose his illness, but thanks to a chance meeting this mystery will be solved; a woman undergoes a risky left temporal craniotomy.

A teenager is rushed to the hospital after taking aspirin to help alleviate altitude sickness; a woman has pain in her arm that mysteriously spreads.

A woman and her husband decide to start a family after numerous negative pregnancy tests; a man appears to suffer an embolism

Trisha and David Kielb's baby is born, but soon afterwards the heart stops, turning their joy into fear; a woman experiences excruciating headaches.

A three-year-old's unexplained vaginal bleeding sends her parents searching for answers to help their baby girl. Also, a student plagued by cramps is unable to hold her food down.

A 12-year-old girl experiences abdominal pains and severe headaches until she is diagnosed with a retroflexed odontoid and Chiari One malformation; a firefighter and paramedic is diagnosed with acquired immunodeficiency syndrome (AIDS).

A 3-month-old boy has breathing difficulties; a woman has stomach problems; stepping on a crochet hook causes strange problems for a patient.

A woman has shortness of breath, chest and joint pain, extreme fatigue, and a cough; strange symptoms appear in an energetic kindergartener.

A husband is rendered helpless by back pain. An overweight girl experiences dizziness and shortness of breath with any physical exertion.

Lavelle Fernandez and Roddy Palma's baby girl inexplicably turns blue 30 minutes after her birth; Laurie Scott suffers from excruciating headaches that won't go away.

A mother rushes her toddler to hospital when she loses the ability to walk or stand. Plus, a runner tries to sleep off a numbness in his foot, but finds the sensation spreading.

Since birth, Ricky is plagued by respiratory infections and a bizarre inability to grow. Noel is a healthy, active man until mysterious spasms start taking over his life.

Harry's body starts to undergo a mysterious transformation. Sadie finds herself on the brink of starvation after her doctor dismisses her complaints.

Brenda and Jake are delighted when their daughter Isabel is born, but their euphoria quickly turns to panic when Isabel stops eating and her skin turns grey. Noah and Alexis were healthy twins until they suddenly lost all their milestones. Charlie, an active pastor, has difficulty reading; doctors must act quickly to save his eyesight.

When Kylie is born struggling to breathe, doctors aren't sure whether they will find a cure. Also, athlete Michael is left fighting for his life when a sore throat turns deadly.

An 18-month-old baby suddenly starts screaming one afternoon in the pool, and begins exhibiting extremely painful symptoms when exposed to sunlight, with porphyria later found to be the culprit. A mother of two children begins to suffer a series of very debilitating headaches.

Diane finds two small, red bumps on her foot; within hours her foot is swollen and appears black and blue; despite undergoing tests, the medical team has no diagnosis.

After blisters appear all over the body of young Julie McCawley, she appears to have Stevens-Johnson syndrome; Conor Heybach's weight gain and uncontrollable appetite is a mystery until a doctor discovers he has Prader-Willi syndrome.

After moving houses, and months of strange behavior, 12-year-old Sammy stops walking and only hops; the doctors are the only hope to discover the cause of his bizarre symptoms. He is eventually diagnosed with PANDAS, a condition in which antibodies mistake his brain for Streptococcus bacteria.

After suffering a series of debilitating incidents believed to be the result of Crohn's disease, Karen, an albino, has to have most of her colon removed. Several decades later, at the age of 38, she receives a phone call from someone who suggests she is suffering from a rare and fatal disease, Hermansky-Pudlak syndrome, which is also the cause of her albinism.

A girl sleeps for ten days in a row, but tests are normal and doctors are perplexed; a marathon runner experiences unexplainable fatigue.

June has a biopsy and, when a mark appears on the site, she has surgery, leaving her with a growing open wound. Her doctor diagnoses her with a flesh eating virus. Can June's life be saved?