'Never experienced this level of pain' - Former All Black Adam Thomson's mystery illness finally diagnosed

Former All Black Adam Thomson's mystery illness has finally been diagnosed after becoming ill in Japan. 

Thomson, 35, is currently in Japan playing for the Canon Eagles, and was rushed to hospital last Tuesday after suffering excruciating back pain which left unable to walk.

Doctors now say he has Lumbar Discitis, a rare spine infection. 

Thomson's partner Jessie Gurunathan says he's relieved he has an explanation. 

"He felt so helpless not being able to identify why he was in this much pain," she told 1 NEWS.

"He's never experienced this level of pain."

The 29-Test forward has been posting about his ordeal on social media. 

"It's been a tough week full of unexpected challenges," Thomson wrote on Instagram.

"It's going to be a long road to get back on my feet but I'm up for it."

Thomson is expected to make a full recovery.