World boxing champion Manny Pacquiao left hospital on Tuesday following treatment for an ulcer possibly brought on by his campaign for a seat in parliament. Pacquiao, 31, who was taken to a hospital for stomach pains on Sunday, said he was suffering from an ulcer which may have been caused by irregular eating habits during his recent political campaign. 'I must be disciplined and not miss meals during the proper time,' he said in an interview with ABS-CBN television. The 31-year-old fighter, who was elected on May 10 to represent the impoverished southern province of Sarangani, has been preparing to take up his post in the Philippine parliament. Boxing promoters are also working to arrange a bout between Pacquiao and American Floyd Mayweather in November, to settle once and for all the fighters' claim to be the best fighter, pound-for-pound, of their generation. Asked about the fight, Pacquiao replied: 'Wait to see if (the fight with) Mayweather will push through. It is hard to say. Mostly, we hear a lot of talking.' Negotiations for a Pacquiao-Mayweather fight fell through earlier this year when the American insisted on Olympic-style random drug testing, which the Filipino rejected as too intrusive before a bout. Boxing victories as well as his commercial endorsements last year made Pacquiao the world's sixth-highest paid athlete, with earnings of 40 million US dollars, according to Forbes magazine. 