this MIGHT hurt

Collywobbles

Definition:

pain in the abdomen and especially in the stomach; a bellyache

Example:

"... unfortunately I awoke this morning with collywobbles, and had to take a small dose of laudanum with the usual consequences of dry throat, intoxicated legs, partial madness and total imbecility..." — Robert Louis Stevenson, Vailima Letters, 1890-1894

About the Word:

Etymologist believe that collywobbles most likely has its origin in cholera morbus, the Latin term for the disease cholera (the symptoms of which include severe gastrointestinal disturbance).
How would cholera morbus have shifted into collywobbles? By folk etymology – a process in which speakers make an unfamiliar term sound more familiar. In this case, the transformation was probably influenced by the words colic and wobble.