This is the chord progression of Bellyache by Billie Eilish on Piano, Ukulele, Guitar and Keyboard.

[Intro]
C Am Em
C C/G Am Am* Em Em/B

[Verse 1]
C                C/G
Sittin’ all alone
Am                Am
Mouth full of gum
Em Em/B Em Em/B
In the driveway
C                              C/G
My friends aren’t far
Am                Am
In the back of my car
Em Em/B Em Em/B
Lay their bodies

[Pre-Chorus]
C    C/G    Am      Am
Where’s my mind
Em     Em/B    Em    Em/B
Where’s my mind

[Verse 2]
C                              C/G
They’ll be here pretty soon
Am                              Am
Lookin’ through my room
Em Em/B E Em/B
For the money
C                C/G
I’m bitin’ my nails
Am                              Am
I’m too young to go to jail
Em Em/B Em Em/B
It’s kinda funny

[Pre-Chorus]
C C/G Am Am
Where’s my mind
Em Em/B Em Em/B
Where’s my mind
C C/G Am Am
Where’s my mind
Em Em/B Em Em/B
Where’s my mind

[Chorus]
C
Maybe it’s in the gutter
Am
Where I left my lover
Em
What an expensive fate
C
My V is for Vendetta
Am
Thought that I’d feel better
Em
But now I got a bellyache

[Verse 3]
C
Everything I do
Am
The way I wear my noose
Em
Like a necklace
C
I wanna make ’em scared
Am
Like I could be anywhere
Em
Like I’m wreck-less

[Pre-Chorus]
C Am
I lost my mind
Em
I don’t mind
C Am
Where’s my mind
Em Em/B*
Where’s my mind

[Chorus]
C
Maybe it’s in the gutter
C/G Am
Where I left my lover
Am* Em Em/B Em
What an expensive fate
Em/B* C
My V is for Vendetta
C/G Am
Thought that I’d feel better
Am* Em
But now I got a bellyache

C
Maybe it’s in the gutter
C/G Am
Where I left my lover
Am* Em Em/B Em
What an expensive fate
Em/B* C
My V is for Vendetta
C/G Am Am*
Thought that I’d feel better
N.C.
But now I got a bellyache