I think it's worth noting that Frank has been downplaying how bad things were. Everyone talks about his addiction and why benzos and the Santos and Robby of it all, but I don't think I've seen anyone acknowledge the simple truth that Frank fucked up his spine enough to be put on benzos in the first place.
Because where Robby has back pain that's a result of overuse and seemingly located more heavily in lower back. It's a strain issue. Frank was put on benzodiazepines which means it was a muscle/nerve issue. Specifically we know he was stealing Lorazepam, which hits fast and hard for all my people who have never been prescribed Ativan for anxiety. Fifteen minutes after taking and you will feel better. It's also known to treat convulsions, insomnia, and it's a muscle relaxer used to treat muscle spasms and pain.
And while it would be easy to look at the situation and think he continued using after he was better, Frank did "not getting better" type damage to his back. It's never explicitly noted, but we see it most clearly in Season 2, Episode 11 when he goes to pick up Micah.
We know from the testing that if Micah should weight approximately 25kg, that's 55 lbs. He's probably about five or six (a little older than Tanner) and Frank is hurting picking up him.
Catch the grimace the moment he scoops up Micah? Notice at the way his jaw clenches when he gets him from the car like he's bracing himself himself before doing what he must?
Or the way the pain steals away from Frank's breath and focus when he sets Micah down. Like this is a man in clear and active pain dealing with a small child.
For perspective, we're talking about the weight of a 65 inch tv or 5 gallons of paint. Hell, a large dog weighs about that much. And Frank can't handle that.
I mean, for all of you that have never done nerve damage to your spine: take up stretching and pray to whatever higher power you have. But also, muscle spasm pain is a sharp, blinding pain that will bring tears to your eyes and send you rushing to the Emergency Room if it's bad enough. And the treatments are limited (drugs, PT, and surgery are the only real options and Frank hardly has time for the last two, nor are they guaranteed long term fixes).
But we're not seeing Frank cop to that simple truth. He can't do Benzos, but his alternative is pain. It is suffering. And it makes sense that he keeps insisting that he has suffered so much in the aftermath because he is, physically. He is taking all that pain and not saying anything. He's not making a fuss. He's making his back issues worse to prove how much he has changed.
Except all he's doing is not just setting himself up for failure, but underscoring of how he got to where he is.
He's always felt that pain in his back. The addiction wasn't just for the love of the benzos, but because he is still feeling a clear pain six months after the incident. And sure, he told Robby about the accident in some capacity prior to season one, but he keeps the depths of it to himself until he can no longer contain it. Which feels like something to watch for heading into season 3 because that pain is only going to get worse.