UK pop star Robbie Williams has revealed he is battling a mystery illness, but won't say what it is.
The recently married singer says he misdiagnosed himself with depression four years ago, but recently discovered he was actually ill with something else.
"I thought I was lethargic and depressed as a person. I thought that was my make-up," he told UK radio station Magic 105.4 in a recent interview.
"I found out a few months ago that I'd been ill, completely by mistake, and I don't want to go into the whys and wherefores but what I had made you lethargic and made you depressed and I'd had it for years and not known and I'm on treatment for it. It's changed my life."
The 36-year-old singer has experienced a number of disappointing moments during his career, including being in debt of £500,000 ($835,000) after leaving pop group Take That 15 years ago.
"Superstardom gets everyone in the end," he said.
"I don't think anybody's responded to it particularly well when they get to a certain level. Elton John went mental, Elvis went mental, I went mental. Everybody at some point, at that stage, goes bonkers."
The singer also revealed that one of his biggest mistakes was covering George Michael's song 'Freedom' as his first solo single.
"I recorded 'Freedom' to kind of get the record company off my back," he said.
"And basically, the video to 'Freedom', I did all the lip-syncing to George Michael's version because I hadn't recorded my version yet.
"And also I was in a bad, bad, way. I was pre-rehab and I'd just finished off the top drawer of the mini-bar, the whole top drawer, all the liqueurs and spirits, and then started the video.
"I was in a very, very bad way so I wasn't making the best choices then as you can imagine. I realised that I'd got to go off to rehab, I was an alcoholic."