Derrick Lewis is headed to Germany to undergo stem cell treatment for his chronic back problems. If that doesn’t work, the UFC heavyweight isn’t sure what he’ll do – other than fight through the pain.

“I’ve been dealing with it for years,” Lewis told MMAjunkie Radio on Monday. “Each fight, I have the same problem. Sometimes, it’s not as bad as it’s been the last couple.”

Lewis (20-5 MMA, 11-3 UFC) noted he’ll be working with the same group that helped former UFC bantamweight champion Cody Garbrandt, whose back problems forced him to withdraw from a title defense last year against now-champ T.J. Dillashaw.

“I’m working on it right now as we speak,” Lewis said.

Known for his heavy-fisted aggression, Lewis was a shell of himself this past Saturday as he limped through three rounds with Francis Ngannou at UFC 226. Although he won a unanimous decision, his injury kept him from fully engaging.

“It’s a win for sure, but it really does feel like a loss,” Lewis said. “I’ve got no kind of relief or satisfaction at all. Usually, a couple of days after the fight, I’m real satisfied. But I still feel tense about the whole situation.”

Ngannou (11-3 MMA, 6-2 UFC) didn’t do his part, either. The one-time heavyweight title challenger apologized for his performance and said he let fear control him in the cage. Lewis agreed.

“I looked at him in his eyes and his face, and it wasn’t even the same guy that I saw at weigh-ins,” Lewis said. “He looked completely different. His soul had already completely slipped out of his body before he even stepped in the cage.

“I’ve seen that same look in Gabriel Gonzaga’s eyes when he stepped into the octagon with me, that he was already defeated.”

UFC President Dana White called the bout an “abomination” and blasted Ngannou for what he thought was an overinflated ego. Lewis got a pass for his injury, though White cautioned it could be a career hindrance.

Two days after the fight, Lewis hadn’t watched it and doesn’t intend to. He remembers being worried about getting countered by Ngannou, and still pushing forward, only to get no response.

Coupled with his injury, Lewis was unable to get the ball rolling.

“I was even bored in the fight,” Lewis said. “I felt like I pushed forward more than he did, and I got so bored, and I started listening to the chants. It really did sound like a surround sound in the stadium.”

Afterward, Lewis said a cageside doctor approached him and immediately felt the back spasms that had seized his back. He didn’t need any confirmation.

Now, he just needs a fix.

“We’re going to try two more things and see what the doctors can do,” Lewis said. “But if not, then I’m going to have to continue fighting with this same injury.”

For complete coverage of UFC 226, check out the UFC Events section of the site.

MMAjunkie Radio broadcasts Monday-Friday at 1 p.m. ET (10 a.m. PT) live from Mandalay Bay Resort & Casino’s Race & Sports Book. The show is hosted by “Gorgeous” George Garcia, Brian “Goze” Garcia and Dan Tom. For more information or to download past episodes, go to www.mmajunkie.com/radio.