The rock world was thrown into mourning on Monday (28Dec15) when it was announced that the frontman had passed away four days after his 70th birthday following "a short battle with an extremely aggressive cancer."
His manager Todd Singerman has now revealed Lemmy went to hospital two days after his star-studded birthday party at Los Angeles' Whisky A Go Go club on 13 December (15) because he was feeling unwell.
He underwent a barrage of tests, and doctors discovered he had terminal cancer which had spread to his brain.
Singerman tells Sky News, "Nobody had an idea (sic), we just learned Saturday, two days ago (sic), that he even had cancer and the doctor told him he had between two to six months to live. He goes (dies) today as I was making calls to (bandmates) Phil and Mikkey telling them to come on out so they could have a last goodbye while he was still upbeat and everything. He was feeling mighty low... He wasn't expected to die like that...
"He (Lemmy) gets home (from tour), we have a big birthday party for him at the Whisky A Go Go. His friends came down and played. Two days later I could tell he wasn't feeling good so we took him to the hospital, they release him, then after the brain scan they found the cancer in his brain and his neck... The doctor comes with the result a couple of days later and says... it's terminal."
Singerman explains Lemmy was initially released from hospital because doctors "said everything was fine" but they decided to take the rocker for a brain scan because "his speech was seeming a little odd, we wanted to see if maybe (he had) a minor stroke."
Singerman goes on to admit he was surprised that Lemmy's condition was not spotted earlier because the rock veteran had been battling a number of health issues over the last few years.
"That caught everyone by surprise," he adds. "That (cancer) was the last thing we thought he would ever have. When you think about it he has been to every doctor and hospital around the world and nobody caught that... That comes as a massive shock."