This is from a light novel I'm reading. Here's the part that I'm having trouble with this sentence:
Based on what I know regarding the rest of the sentence, I believe that this translation should be something like:
I developed a headache as I thought it over.
According to my electronic dictionary, 巡らせ should be the imperative form of 巡らす. But I'm having trouble reasoning out why the imperative would be needed here since he's thinking it over himself and not being commanded by someone else to think it over.
If you need more context, here's the passage that I'm looking at: