莫名其妙的烦，心里闷闷的，不知道烦恼的原因?

A baffled one irritated, bored a bored one in the heart, know the worried reason

indescribable worry ,bored in the mind,be insensible of the worry.
这个很标准的，不过要是加上主语就更好了

Absurd being tired of , the vexed cause in the heart, suffocative , not know?

troubled, depressed, and not knowing why