Complex sentence: Although Keats managed to write many poems in 1819, he was suffering from a multitude of financial troubles throughout the year, including concerns over his brother, George, who, after emigrating to America, was badly in need of money.
Split into simpler sentences: Although Keats managed to write many poems in 1819, he was suffering from a multitude of financial troubles throughout the year. These troubles were compounded with his concerns over his brother, George, who, after emigrating to America, was badly in need of money.