When somebody have something in his mind and is thinking about it too much time, something that worry him or something that can't solve.

When somebody has difficult choices and has been thinking a lot about them.

Normally the expression involves "for a long time".
I have been chasing my tail about the problem in the department for two days, but I can manage to find a suitable solution.

I have been chasing my tail for three weeks about the holidays and I still don't know where to go.
by Gustavo Muñoz February 16, 2009
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