Miley Cyrus was released from the hospital just last week following an allergic reaction to the antibiotic Cephalexin.
But now it seems the singer has suffered yet another health setback, forcing her to cancel a concert in Amsterdam that had been scheduled for May 2.
There is no official word yet on the severity of Miley's illness, but sources say that "her allergic reaction has returned."
Amsterdam was to be the first stop on the European leg of Miley's Bangerz tour and she is expected to also postpone a show in Antwerp that was supposed to take place on May 4th.
Miley hasn't issued a statement on the cancelation yet, but there is speculation that she may be forced to postpone her entire tour until she is back to full health.
An insider close to Miley assures fans that "Miley is very bummed about it."
Miley had tweeted about her frustration at being forced to cancel tour dates during her previous hospital stay.
Rumors have circulated indicating that Miley overdosed on drugs resulting in her extended hospitalization.
The singer has denied that her illness is the result of anything other than a severe allergic reaction.
Doctors had previously warned her that her negative side effects could resurface any time within a month when she stopped taking the antibiotics.