Its a very bad idea to take someone elses medication, and it is not going to impress your doctor.

Depending on what medication you are on now, it could have had a serious drug interaction, and the dose could have been wrong for you.

If your supposed to be on Strattera, why are you not taking it?

I suggest the most important thing you can do, is be entirely honest with your doctor, tel them what is going on with you, what medication you are and are not taking, etc.