Ben Jacobs has spoken of the mysterious set of symptoms that have kept him out of action since Round 16 last season.

On the end of a fierce sling tackle suffered against the Lions in Round 11, Jacobs says he then began feeling a bit "off".

“At the time of the whiplash incident, I remember my neck being really sore," he told North Media in a special podcast episode.

After playing the following week against Geelong, things took a turn for the worse.

"Each week I was like, "can I play?" and I literally did the main session two or three times, expecting to somehow play, and I wasn’t able to for a number of weeks there."

The injured North Melbourne midfielder admitting much is still unknown about his condition.

“I sat down with the doctors the Monday of the week leading into the bye, and that’s when things weren’t really adding up and I was getting worse,” Jacobs told North Media in a special podcast.

“The worst part about it was I didn’t know what was going on, and I still don’t.”

The 27-year-old recounts the lengths he and the club went to in order to identify exactly what was wrong with severe head pain, lethargy and a sore neck taking a toll.

"I did have a sinus operation, and whatever I did have wrong with the sinuses is gone now, but it wasn’t the cause of this,” he said.

“I had a little nerve block in the neck, in a nerve that translates to the front of the forehead, and people can get chronic headaches from that, so I burnt that nerve off in the neck.

“It’s been a ten or eleven month process of finding out what’s happening and what’s wrong.”

Listen to the full podcast here: