Michael Johns Dead -- 'American Idol' Contestant Dies at 35

5:00 PM PST -- Sources close to Michael Johns tell us he went to a doctor on Thursday to check out the pain he had been feeling in his ankle ... the swelling and bruising had made their way up to his leg.

Doctors didn't find any problems however -- so they cleared him to go home.

We're told the next afternoon at his friends apartment ... Johns' body was found on the couch unresponsive. When paramedics arrived, he was already dead.

"American Idol" finalist Michael Johns died Friday at the age of 35.

The singer's death was caused by a blood clot in his ankle ... sources tell us he had twisted his ankle earlier and was in a great amount of pain.

People close to Johns tell us ... it appears the ankle injury triggered the clot. We're told he died in his sleep.

The singer placed 8th in Season 7 (2008) and following his exit from the show he continued to record music. He recorded an album -- "Hold Back My Heart" in 2009.

He'd also done a tremendous amount of charity work with former executive producer Nigel Lythgoe.

Lythgoe tells TMZ, "He was a great talent and dear friend. My boys and I are devastated."

Johns was married to Stacey Vuduris. They married in 2007.

The singer's family says, "Our family is devastated by the passing of our beloved Michael, a wonderful husband, son, brother, uncle, and friend. We appreciate the outpouring of love and support we have received from all corners of the globe."

The last time we shot Michael he was in great spirits.