"bitter days" is correct and can be used in written English.
You can use it to describe days that are unpleasant or difficult. Example: "I had a few bitter days when trying to find a job after college."
Those bitter days seem long ago now.
Smith didn't have enough votes, either, and the balloting played out over several bitter days.
After two and a half bitter days, the battle against the terrorists who struck Mumbai on Wednesday is over.
Not for Vivie the poverty-stricken, bitter days of Mrs. Warren's youth: MRS. WARREN: It can't be right, Vivie, that there shouldn't be better opportunities for women.
Meanwhile, a whole new gen eration has grown up, which knows nothing about the bitter days of the war, to say nothing of prewar times.
Then Rana al-Uqbani, a journalist who had been captured by the Qaddafi forces, called to tell me that my beloved friend the poet Rabi Sharir had been rescued by the rebels after suffering through some bitter days.
So when the German chancellor speaks of a "bitter day" and a "painful defeat", the bitterness and pain are real.
"This is a bitter day for us," Mr. Röttgen told supporters.
"Today is a very bitter day," Mr Röttgen conceded last night.
"It is a bitter day, a day of mourning for democracy," he told the crowd, adding that other leaders, including Beppe Grillo, the former comedian and head of the antigovernment Five Star Movement, were powerful figures in politics despite not holding office.
