a sta ca pe ace / foc / ghimpi / jar / jeratic / mărăcini / spini / cărbuni aprinşi

to be / to sit (up)on pins (and needles)

to be on tenterhooks

to be / to sit (up)on thorns

to be all on edge

to have a rough time

to be in a stew / in hot water

amer. to be on anxious seat

to stand upon burning coals

to be on fire / on the gridiron

to be on hot bricks.