United Kingdom, Aug. 4 -- Justin Timberlake was ill for "months" before being diagnosed with Lyme disease.

The 44-year-old singer revealed last week he had contracted the tick-borne condition - which can cause symptoms ranging from nerve pain and fatigue to cognitive difficulties and chronic illness - and insiders have told how he initially thought the exhaustion and pain he had been experiencing were part of getting older and the demands of his two-year Forget Tomorrow world tour.

The source told People magazine: "He's not 20 anymore. But when his symptoms worsened, he realised something deeper was going on.

"He pushed through for months before finally getting answers. The Lyme disease diagnosis brought clarity to a series of unexplai...