while back Идиома
while back|while
adv. At a time several weeks or months in the past.

Used with "a".
We had a good rain a while back, but we need more now. Grandfather is well now, but a while back he was in the hospital for three weeks. See: CRACK THE WHIP.
a while back
a while back Also,
a while ago. Some time in the past, as in
I ran into Barbara a while back but didn't get her new address, or
John wrote me a while ago about his new baby. This term uses
a while in the sense of “a short or moderate time,” a usage dating from about 1300.
while back
while back see
a while back.
a while back
At some point in the past. I bought this dress a while aback but accept never had a adventitious to abrasion it.Learn more: back, whilea while back
Also, a while ago. Some time in the past, as in I ran into Barbara a while aback but didn't get her new address, or John wrote me a while ago about his new baby. This appellation uses a while in the faculty of "a abbreviate or abstinent time," a acceptance dating from about 1300. Learn more: back, while