Complex sentence: After returning to Los Angeles, Kaufman consulted a physician where he checked himself into Cedars-Sinai Hospital for a series of medical tests and a few days later, he was diagnosed with a rare type of lung cancer.
Split into simpler sentences: After returning to Los Angeles, Kaufman consulted a physician, after which he checked himself into Cedars-Sinai Hospital for a series of medical tests. A few days later, he was diagnosed with a rare type of lung cancer.