My dad had a bulged disc years ago. Unlike some others it wasn't terrible right from the start. Started as just mild pain and then slowly deteriorated to extreme pain, until it got to the point where he could not get out of bed and, without exaggeration, he talked about wanting to die.
Pain killers kept getting escalated. First he self regulated with Advil, T3's, eventually morphine, and I think perccocets...eventually nothing worked except straight up oxy's. At that time we knew they could be addictive but nothing else worked at all the pain was so bad.
He was weeks away from surgery when one day the pain started to subside and he just ended up making a full recovery on his own. Crazy. And had no problem giving up the oxy's.
I guess my point is the pain can definitely progress and be unbearable. If it happened again, knowing what we know now about oxy's, I'd probably do a deep dive into some of the cannabis options for pain relief. I have no idea myself if it works for this kind of thing, but I do know some people with chronic injuries and even cancer who used it to get off pain killers and function day to day. They absolutely swear by it.
Good luck! Hope he feels better and gets the surgery soon. Herniated discs are the worst.