"small headache" is correct and usable in written English.
You can use it to refer to a mild headache that is not severe. For example: "I had a small headache this morning, but luckily it didn't last for long."
In his response, Mr. Pawlenty may have created a small headache for himself.
This has been no small headache for Mr. Thompson, the city comptroller and Democratic candidate, who is fighting an uphill battle to defeat Mayor Michael R. Bloomberg.
The claims by Greece and Italy have been no small headache for Mr. Brand, who inherited the problem along with a legacy of management turmoil when he took over as director at the beginning of the year.
Another girl wrote, 'Yes — Sandy was sick.' And a boy — one of the few boys — wrote, 'Yes, and after Sandy got sick and there was a fire drill, and when everybody was walking out of the building, I felt like a small headache.' Well, you get the drift.
But in spite of the beauty surrounding us, my hands began to tremble and a small headache appeared from nowhere.
This is a confirmation of discriminating features of FM previously detected in a smaller headache series [7] with the inclusion of physical component of quality of life.
In this study, which is the extension of the previous one in a smaller headache series [7], we found a lower frequency of FM representation in the selected patients.
I write often on the need to plan ahead for taxes, especially if you want to keep more of your money, get a bigger refund, have a smaller headache at tax time, and for many other reasons.
Retailers are facing smaller headaches, too.
Oscar-winning film editor Walter Murch certainly has clear opinions on 3D's future: "[It's] dark, small, stroby, headache inducing, alienating.
"So: dark, small, stroby, headache inducing, alienating.
