The 26-year-old singer paid £35,000 last October to have her modest bust increased to a generous D-cup. She has had a number of problems with the implants, and was reportedly "terrified" when her boobs began hurting again earlier this week.
By Thursday evening, the pain was unbearable and Amy was rushed to the same private surgery clinic that originally performed her breast enlargement. Doctors kept her under observation all night, while they conducted a series of "urgent" tests. She has now been allowed to return to her Camden home, to await the results of the tests, which will tell her whether she must undergo corrective surgery, or even have the implants removed.
"Amy was in agony and became convinced it was something to do with her boobs," a family friend said. "She thought she would leave it for a while but the pain got worse.
"She went into the clinic on Thursday and they kept her under observation. She is waiting for a decision on whether the implants have to come out or not."
Amy is said to be extremely worried about the test results. She loves her new breasts, and has been flaunting them in a series of low-cut tops since having them enlarged last year.
"Amy loves her curves and would hate to have to have them taken out," the source told British newspaper The Sun. "She is still her bubbly self but she is worried."
Amy was also treated for complications relating to her breast implants in November.