Relaxed but looking tired, Pope Francis has resumed to his post as spiritual pontiff of the 1.2-billion strong Roman Catholic faith, appearing on Sunday at a two-hour-long Mass in St. Peter's Basilica. Concerns are growing for the pope's medical situation as he has been abruptly cancelling appointments lately, or at least four times in the last seven months.

A report by the Irish Independent said the pope's very first sick leave call was in December, when the Roman Catholic pontiff postponed a meeting with Cardinal Angelo Scola of Milan and organisers of the World Expo. The second was in February when he cancelled a visit to Rome's major seminary.

A scheduled visit to Rome's Shrine of Our Lady of Divine Love on May 18 was cancelled, where Vatican explained so that the pope can have ample rest before embarking on his Holy Land trip on May 24-26.

For June 2014, Pope Francis has cancelled three appointments for the month alone. The Vatican has maintained all throughout the abrupt cancellations that the cause was just a "minor sudden indisposition."

Read: Pope Francis Takes Day Off, Nothing Major Says Vatican, Just Tired, Advisers Keen on Doomsday Conspiracy Mill

This still excludes the announcements Vatican made concerning his audiences and daily masses schedule for July and August.

Read: Pope Francis Cancels July Appointments, Raises Question If Vatican Is Hiding Declining Health

The Vatican, as expected, consistently declined to provide details regarding the abrupt cancellations nor refused to expound on the pope medical's condition.

On Friday, Jesuit Fr Federico Lombardi, a Vatican spokesman, apologized to the people who had gathered at Rome's Gemelli hospital waiting to see Pope Francis. Angelo Scola, Cardinal of Milan, was instead sent to read a homily in his place.

"Because of a sudden ailment, the Holy Father will not go to the Gemelli for the announced visit," Fr Lombardi said.