Madonna Is ‘Feeling Strong’ and Back in Rehearsals for Her ‘Most Ambitious Tour Ever’: Source (Exclusive)

“She’s so happy to be back onstage,” a source tells PEOPLE exclusively of the superstar, who was hospitalized in June for a bacterial infection The Queen of Pop is ready to reign again. After being hospitalized in late June for a “serious bacterial infection,” Madonna is back at work and gearing up for the launch of her Celebration Tour, a…