David Walliams has admitted he is still suffering following his gruelling charity swim in the Thames.
The 40-year-old star has dismissed reports that he's been tested for Weil's Disease, a waterborne bug passed on through contact with infected animal urine, mainly from rats, following the 140-mile September charity effort.
But he said: "I've got a parasite in my stomach which is making me feel sick all the time and I've a torn disc. I'm not crippled, but I'm not back to 100% fitness.
"The stomach bug has been a long process and I'm going to see another doctor about it.
"Normally it works itself out of your body, so that's what I'm hoping will happen."
The Little Britain star said he's not sure he'll ever be able to top what he did for Sport Relief.
"There's a point where you think your body can't take any more. And then, you have to do more than you did the last time to keep it interesting, to do something harder. I'm not sure I'd be able to do that," he said.
"But it's addictive because helping people and changing people's lives gives me a huge buzz. And the sense of achievement is great."
:: David Walliams' latest book Gangsta Granny is published by HarperCollins.