Samuel Luther "Big Sam" Thompson (March 5, 1860 - November 7, 1922) was an American professional baseball player from 1884 to 1898 and with a brief comeback in 1906. At 6 feet, 2 inches, the Indiana native was one of the larger players of his day and was known for his prominent handlebar mustache. He played as a right fielder in Major League Baseball for the Detroit Wolverines (1885-88), Philadelphia Phillies (1889-1898) and Detroit Tigers (1906). He was inducted into the Baseball Hall of Fame in 1974.

At age 36, Thompson played his last full season of professional baseball in 1896. His average dipped to .298, but he still managed to collect 100 RBIs. Thompson's throwing remained strong as he turned in one of the finest defensive performances of his career. Despite appearing in only 119 games in the outfield, he led the league in outfield fielding percentage (.974), outfield assists (28), and double plays from the outfield (11). One sports writer noted that, even at age 38, Thompson "possessed an arm that the fastest sprinters in the big league had a lot of respect for." As a team, however, the Phillies fell to eighth place in the National League with a 62-68 record.  In 1897, at age 37, Thompson was sidelined by pain and appeared in only three games. Some accounts suggest that Thompson's absence from the lineup may have also been the result of his not getting along with Philadelphia's new manager George Stallings. Without Thompson, the 1897 Phillies dropped to 10th place with a 55-77 record.  Before the 1898 season began, Thompson gave an interview in which he questioned the Phillies chances to compete in 1898: "What are the Phillies' chances this season? Six clubs, Cincinnati Baltimore, Boston, New York, Cleveland and Brooklyn are bound to beat them, and they will have to fight hard to lead the second division, and I very much doubt if they can do that." Though his loyalty to the Phillies was questioned, Thompson did return in 1898 and was batting .349 with 15 RBIs, five doubles, three triples, a home run after 14 games. However, Thompson opted to leave the team in May 1898 and return to his home in Detroit. His sudden retirement has been attributed to a "combination of homesickness and chronic back pain." Other accounts indicate that continued tension with manager Stallings contributed to Thompson's decision to retire.

Answer the following question by taking a quote from the article: where did he have pain
His sudden retirement has been attributed to a "combination of homesickness and chronic back pain."