To blow an issue or event out of proportion: “You have only a small blister on your heel, but you complain as though you broke your leg. Why are you making a mountain out of a molehill?”
make a mountain out of a molehill
Exaggerate trifling difficulties, as in If you forgot you racket you can borrow onedon't make a mountain out of a molehill. This expression, alluding to the barely raised tunnels created by moles, was first recorded in John Fox's The Book of Martyrs (1570).