What is wrong with King Juan Carlos, 73

What is wrong with Spain's King Juan Carlos, 73, who seems only a shadow of his vigorous, dynamic and joke-cracking former self?
Speculation has soared about the monarch's health since he was seen leaning on a walking stick, looking pale and sickly, at a literary award ceremony two weeks ago.
Prior to that, Juan Carlos failed for the first time to attend the traditional Easter mass at Palma de Majorca cathedral. The palace said he stayed away to prepare himself for the Qatari emir's visit, but few Spaniards were convinced by that explanation.
Rumours about the king's poor health first took off when doctors removed a tumor from his lung a year ago.
The tumor was discovered less than two weeks after Juan Carlos had passed his annual health exam with flying colours.
Doctors said the tumor was benign and excluded any risk of lung cancer. The lung operation nevertheless forced Juan Carlos to give up his beloved Havana cigars.
Since then, the royal palace has repeatedly denied rumours about the king's declining health, attributing his walking difficulties to hip and knee injuries he sustained while pursuing interests in skiing and other sports in the 1980s and 90s.
A palace spokesman also commented on red spots that had been seen on the monarch's face, telling the news agency Europa Press that they had been caused by overexposure to the sun.
Juan Carlos has maintained a normal travel schedule over the past year, visiting several Gulf countries, Argentina, Russia, Germany and Morocco. He is now set to make a state visit to Switzerland later this week.
Such arguments failed to convince medical experts interviewed by the daily El Mundo, who said the king 'must have something.'
Juan Carlos' health is a cause for genuine worry for many Spaniards. The king enjoys a widespread popularity since thwarting a coup attempt in 1981.
For several years now, Juan Carlos has allowed Crown Prince Felipe to take over many of his official duties, but that is seen as forming part of the prince's education rather than reflecting the monarch's state of health.
The possibility of the king abdicating in favour of the 43-year- old prince is not the cards, as Queen Sofia clearly told her biographer Pilar Urbano in a recent interview.
'To abdicate? Never! The king will never abdicate ... Only death can make a king retire,' Sofia said.