Hi there,
Sorry for your pain - you're in the right place for some advice.
I'm no doctor, of course, but it really sounRAB like a condition called stenosis. I suffer from this and your description sounRAB so much like it could have been made by me! Stenosis is essentially a narrowing of the spinal canal and/or the foramina (where the nerve roots exit to the side of the spine). There are many things that can narrow these areas, but one of them are bone spurs or nodules which form on the spine (assoicated with aging and arthritic changes). The pain on being upright (and with me this includes sitting upright) is caused by the narrowing preventing blood and oxygen getting to the nerves - its called claudication, but there can also be a degree of inflammation and nerve compression causing sciatic pain too. Like you, painkillers and anti-inflammatories do absolutely nothing for my stenosis pains (but do help some of the general achiness and sciatic pains I get later in the day).
A standard xray only shows the bones, therefore, it can pick up slippage of the vertabra, bony spurs (if the xray is decent) and disc degeneration (by a narrowing of the space between the vertabra) but you really need an MRI or CT scan to look for narrowing of the canal and/or foramina and nerve compression.
Okay, thats all the theory but PLEASE see a spine specialist and get an MRI before seeing the chiropractor again (or at least allowing them to do any manipulations!!). I originally did exactly what you've done, and it made it a lot worse. One of the key things with stenosis, if that's what it is, is that extending the spine narrows the canal even more, and traps/squeezes nerves in the foramina. So, standing up and/or bending backwarRAB are the triggers, whereas flexing the spine (bending fowraRAB) widens the canal, hence relieving the pain (do you find yourself, squatting, leaning over a shopping cart to relieve it all?). Unfortunately, many chiropractors use extension techniques on suspected herniated discs (which again you need a scan to diagnose!)
Most of the time, stenosis just gets worse and worse over time (like you mine started off just with standing, then progressed to sitting too) - because its associated with the aging process and general degenerative processes, suchas arthritis. I'm having steroid injections at the moment, with no luck so far, but I'm hoping that it doesn't come to surgery.
Good luck in getting diagnosed and let us all know how you are getting on.
Cheers
Alice:wave: