It is not the first time that the 31-year-old has suffered a head injury, enduring several concussions in the past including in a pre-season game against Edinburgh shortly before his latest setback.
But the lock, who appeared seven times for the Lions on tour last year, insists the symptoms had all but disappeared shortly after the incident.
And he is desperate to show what Leicester have been missing when he makes his first start since the injury against Toulon this weekend.
"If you have a knee injury, it hurts when you run so you know why you're not playing - same with your wrist or arm when you can't lift weights.
"In this case I probably had some very mild symptoms for two weeks. And I've been symptom free ever since.
"I've seen a few specialists and it turns out it might not even have been concussion. There are some things called impact migraines which aren't as bad as concussions. It's as simple as taking a tablet for it."