As someone with back problems due to a pinched nerve, I can tell you some mornings are better than others.
Sometimes the pain meds don’t take effect for about 90 minutes. So one has to do the Charlie Chaplin Box Step and deal with the pain till then.
Maybe he purposely didn’t take pain meds now so that his head would be clear for the news conference.
Given that he had surgery for his obesity some years ago, I suspect it's his internal plumbing that is the problem and not his back. But, just basing that on his past weight problems.
As someone with back problems due to a pinched nerve, I can tell you some mornings are better than others.
Was going through that the past 2 weeks, it’s the worst, never know when you are going to get that knife thrust through the lower back. Fortunately slowly going away.
If you have sciatica which I recently experienced, there are stretches and exercises that can fix it. They worked for me in 2 weeks. If it’s herniated disc or a vertebrae problem, that’s more complicated. Wish you luck since I was also bed-ridden after pulling a tendon in my lower back.