Hi kero.
I’ve had issue with my back on & off from my late teens (now in my early 40’s), I’ve done physio, chiro, & have found the best thing for me is a general exercise program. Currently I use a Swiss ball for a fairly short weight routine (back, biceps, chest, triceps, & situps) twice a week. This seems to strengthen the core muscles fine, & combined with biking seems to be doing the trick fine & I get no problems at all. This despite lifting a 25kg 4yr old a few hundred times a day on the weekend ! My back still gets sore doing work where I’m bent over but if it didn’t I’d be surprised.
I’ve had various experiences with physios & have been fortunate to find one who is absolutely incredible. So if you don’t find a good physio keep looking.
I’ve also had excellent results from my chiro, but find either the exercises provided by my physio, or the general exercise training seem to do the trick.
As per previous advice, get yourself checked out, it’s probably long hours driving, but could be more serious. There’s some excellent advice from TFB about the towel for driving (going to use that one myself) & finding a good physio (always cracks me up how wide the breadth of knowledge on this site is, talk about your mastermind group !).
TFB, I had major issues with low immune system & something very similar to CFS (was never diagnosed as having CFS, just 'undefined viral illness'). Went from super fit martial artist to couldn't train, sick all the time, at least once/year in bed ill for 2 weeks straight. Came across a guy in Melb who taugh Qi Gong Dai, 3-6 months later I was healthy once again. BTW, it's also the best hangover cure I've ever found
Cheers
Mark