Pain--fit, saddle, core, or fatigue?

[Owlie]

When I first started riding, I was experiencing upper arm, upper back, and shoulder muscle soreness, especially on the right, which went away with riding. That stopped being an issue, but I was getting some discomfort even on short rides in the girly bits. I moved my saddle forward about 3 mm. I did a 36-mile ride this weekend, followed by 15 the following day. No mashed girly bits (except for what I can blame on the chamois), just a bit of sit bone pain. However, I'm now getting the arm/shoulder pain again, plus a little pain in the lower back that gets better once I get off the bike. No upper back pain.

Searching the forums and by process of elimination, I have 4 thoughts:
1) Since I've significantly upped my distance (previously, my longest ride was about 24 miles) after not riding much more than 6 or 8 miles at a time, it could just be fatigue from spending more time than I'm used to on the bike
2) Lack of core strength means I'm putting more weight on my hands than I should. This would seem to mesh with the back pain, but I don't know.
3) Saddle isn't adjusted properly, or is just a poor match. Likely. No girly parts pain, but I'm still moving around a bit to find the right spot.
4) Fit issue. This is possible. I don't feel like I'm rolling or throwing myself forward trying to reach anything--I'd expect pain in other places as well. Nothing feels stretched or numb, just like I've been at the gym and did too much lifting. I don't know enough to diagnose anything, of course.

Thoughts? How would you suggest I go about trying to determine what's going on here? Since I'm short on cash at the moment, I would like to leave the fitting for later if possible.

[NadiaMac]

if you are not stably situated on the saddle, it is easy to rely on your arms/shoulders/etc to hold yourself in a proper position. I had this issue with my old ill-fitting saddle -- it was too narrow for my sit bones and i tended to slide to the side or forward unless i kind of held myself in place with my arms (which led to considerable arm/hand/shoulder fatigue). A new saddle has largely eliminated this problem

[Owlie]

if you are not stably situated on the saddle, it is easy to rely on your arms/shoulders/etc to hold yourself in a proper position. I had this issue with my old ill-fitting saddle -- it was too narrow for my sit bones and i tended to slide to the side or forward unless i kind of held myself in place with my arms (which led to considerable arm/hand/shoulder fatigue). A new saddle has largely eliminated this problem

I've definitely had that problem with the stock saddle. That led to all kinds of pain. Replacing it helped a fair bit, but now it's back.

[emily_in_nc]

I tend to get lower back pain early in the season, when I'm untrained, or try to take on too many hills. It goes away the second I get off the bike. So some of it may just be conditioning and getting used to riding more and longer mileage. It's pretty normal to have some discomfort if you go from an 8 mile ride to a 36 mile ride!

[tulip]

Probably a combination of all that you have listed.

Distance--keep riding.
Core strength -- that's easily addressed. Get working on your core. You will feel better all around. I prefer Pilates, but find what works for you.
Saddle--sounds like it works okay for now
Fit--maybe. If you can afford a pro fit, you might benefit from getting dialed in.

I'd focus on the core strength. Along with that is stretching, of course (like yoga, and not when you are "cold").

[Crankin]

Emily!
Good to see you here.