1
general::
Away from one's objective, train of thought, or a sequence of events, It is often put as get or put or throw off the track, as in Your question has gotten me off the track, or The interruption threw Mom off the track and she forgot what she'd already put into the stew. This term comes from railroading, where it means "derailed." Its figurative use was first recorded in 1875.
American Heritage Idioms
2
general::
Phrase(s): off the track
1. Go to off the (beaten) track. 2. Fig. [of comments] irrelevant and immaterial. • I’m afraid you’re off the track, John. Try again. • I’m sorry. I was thinking about dinner, and I got off the track.
McGrawhill's American Idioms And Phrasal Verbs