Translation:Why are you making a mountain out of a molehill?
It could be a regional thing, but I would say "make a mountain out of a molehill" is the most common idiom for this in the US. Wow--it's got a wiki page :O https://en.wikipedia.org/wiki/Make_a_mountain_out_of_a_molehill
... HOLY COW! If you read that wiki article, you'll see that in the first recorded use of the idiom in the 16th century...he also says make an elephant out of a fly!!! Woah! Talk about a coincidence. So I guess that expression must have made its way to English back then, but "mountain out of a molehill" has certainly remained strong in English since.
PS Sorry for the stream of consciousness, but I wrote this as I discovered all of the above hahaha