Miley Cyrus is ''really stressed out'' after injuring her neck.

The 'We Can't Stop' singer can't stop crying after mysteriously hurting herself this week and has been instructed to stay in bed to help it heal as quickly as possible so she can resume promotion for her new single.

The 20-year-old star wrote on Twitter on Saturday (22.06.13): ''In so much pain. I hate being sick. My neck f***ing hurtttttts. #stressed

''Really stressed out. Crying only makes me feel worst but i cant help it. i am finally getting to perform #wcs and now this s***s happening!

''Can't move my neck. Can't breathe. Cant barely speak. Coughing like a MF. WTF?!?! I gotta stop working myself up though (Sic).''

Miley, who is engaged to Australian actor Liam Hemsworth, shared a picture of herself in bed and revealed she woke up with the injury on Friday.

She tweeted: ''Woke up & can't move neck. SUCKS!!!!! SMH (Shake My Head) (not really cause I can't move the damn thangggg!) (Sic)''

Meanwhile, Miley has promised to teach Britney Spears how to ''twerk''.

The singer, who has attracted a lot of attention after performing the dance move, which involves a person shaking, wobbling and bouncing their hips and butt up and down, in her new music video, will show her how to perform the dance if Britney teaches her the iconic dance moves from her video 'Slave For You'.

Britney messaged the former 'Hannah Montana' star on Twitter to ask for her help in perfecting the skill, writing: ''Loving your new video for #WeCantStop @MileyCyrus! Maybe you can teach me how to twerk sometime LOL ;) xo (Sic)''

Miley re-tweeted Britney's request to her millions of followers, and later replied: ''@Britneyspears we could twerk it out in exchange for u teaching me da moves 2 'slave for you' (I've been practicing for the past 10 years)'', to which Britney responded: ''That's a deal im going to hold you 2 (Sic)''