、。
I had a bit of a headache last night.
Literal
Last-night, a-little headache [subject-が] do-[past-した]-[explanatory-の].
頭痛がする ('to have a headache') is the standard construction — Japanese uses する with a range of sensations to express 'have/feel X': 音がする (hear a sound), 匂いがする (smell something), 味がする (taste something), 気がする (have a feeling). The final の is the casual question/explanation marker, used here as a reflective statement (not a question despite its shape — context decides).