The British singer, also known as Lily Rose Cooper, gave birth to her second child, a little girl named Marnie, on Tuesday.
However, Allen has now accused NHS officials of failing to keep in touch with her about her postnatal treatment after she was discharged from hospital on Wednesday.
She used her Twitter account to contact the NHS Direct service, writing: "Hi there, can't seem to find out which hospital's community midwifery team are coming to see me. Discharged Weds (sic) morning!!!!... I'm starting to worry now, and no one answers the phone, or if they do, I just keep getting passed around. Let me know if you can (help)."
Allen received a reply from NHS Direct which urged her to look at the organisation's website and call the appropriate phone number.
The Smile star is also mother to another daughter, Ethel, 18 months, with her husband Sam Cooper.