Jordan Gill lost his WBA international featherweight title after he retired against Enrique Tinoco at the Nottingham Arena on Friday night.
Gill was dropped three times by body shots from the Mexican challenger before trainer Dave Coldwell pulled his man out after eight rounds.
"I'm not going to make excuses but I'm going to," Gill told Sky Sports afterwards.
"I've been on the toilet all afternoon. I think I've got food poisoning, I was not going to pull out on the day, I didn't want to quit in the fight.
"He's a good fighter but that was not me in there. I was terrible, I couldn't do anything in there. Every time he touched me, it felt like I was going to explode.
"I will have to come back another day, but tonight is his, congratulations to him."
A lively opening round saw both fighters commit to attacks with Gill boxing behind his long jab and Tinoco marching forward, throwing punches from every angle.
The pair took turns to switch stances in the second as Gill targeted the body and head while the aggressive challenger landed a decent right.
Tinoco hurt Gill with a body shot and dropped him with a second as they traded at close range in the third.
Gill battled back in the fourth and the Mexican urged him on, but a punishing right hook to the body in the next sent the 24-year-old to the canvas for a second time in the fight.
The Mexican came charging out in the sixth and after trying his luck with an optimistic uppercut and an overhand right, tested Gill's chin with a heavy shot.
Gill briefly slowed Tinoco's charge with a heavy right followed by a combination in the seventh round.
However, the Tijuana native reasserted his authority in the eighth round and floored the champion for the third time just before the bell sounded.
The Cambridgeshire fighter made it to his feet by the count of eight and after returning to his corner was pulled out by Coldwell.