Im sure most of us older MDers have occasional lower back (or any kind) pain. One of the Garrett books suggested stretches beforehand. But what about after you've hurt yourself or just plain sore? Motrin helps some..Any others?
LOL on stretches beforehand. in my opinion , I would need to take a Rest & nap after Stretching (Exercising )
Beforehand . Exercise where you don't get anything material out of it,
makes no sense at all to me. I call walking, digging and getting down and up all the stretching and exercise
a human being needs .
I've heard of businesses where they make their workers Exercise before they start their day.
If I worked at a Place like that, I'd take sick days immediately after I was done Exercising for them. Tell them I need a shower & nap

and of course sue if fired. if I was hired to work Not Exercise.
[ in the Immortal words of Woody Harrelson, "You ever see a lion limber up before it takes down a gazelle ?" ]
I don't get lower Back Pain. I do get upper back pain , But to me that just means time to call it a day
Now Off my soapbox : are you sure it is from Digging & not Swinging
for long periods between digs ? do you have a detecting Harness ?
the Detecting Buddy
or Swingy Thingy
May help.
There are other Brands, But since these are the 2 I have and
use so I Can only vouch for them.
The "Buddy" works better then the Swingy Thingy When I have to wear Heavier
Tops Like Jacket, Coat, or Hoodie.
(the chest Strap on the Thingy is Tight and constricting with Heavy Clothes on,
I don't like adjusting straps, back & forth. )
The Swingy thingy when hunting with a T shirt.
I only get back pain when I do allot of Walking & swinging (Useless Exercise)
If I am in a spot where I am down digging as much as I'm up Swinging,
The rests I get while digging keep me comfortable.