The then Blackburn striker was one of six people detained in an investigation by the National Crime Agency (NCA) after it acted on information passed to it by the Sun on Sunday
The newspaper claimed Campbell was under scrutiny for a yellow card he received in a Championship encounter against Ipswich in December, but he was released without charge last month
The much-travelled 32-year-old forward, who denied any wrongdoing throughout the scandal, is looking forward to concentrating on football now that his name has been cleared, but admits he could have walked away from the game altogether
"There were times when I seriously considered walking away from football and retiring," he told the Independent on Sunday
" But friends and family were very supportive
I guess I was just in a very bad place
"When I put everything into perspective, I had worked far too hard and made too many sacrifices to give football up
Why should I walk away when I had done nothing wrong?
"To my enormous relief, I was called back to Winchester police station last month and they eventually lifted my bail conditions and released me without charge.
"There was no cause for celebration
I was relieved but I still felt a great sense of injustice."
Campbell is currently without a club after leaving Blackburn in July
He joined Millwall on loan in January before returning to Ewood Park in April.
Source : PA