Context: the narrative character is attempting to find a reason explaining his past behavior.
I understand the gist of the above sentence (as seen with my translation attempt below), but I don't understand why there is a 何をどう there.
That time, what I wonder is how to think of what my behavior was?
l'électeur says here
「なに」 requires specific and detailed information whereas 「どう」 only requires rough or vague information. "Specifics vs. Overall Approach", so to speak.
Is the above a case of "specific and detailed information" being sought from the "vague information" the character gathered by thinking, or is my understanding of the 何をどう meaning wrong?