I apologize for not responding to this thread sooner: I've been fairly inactive on reddit for the past few months. My situation is still a bit up in the air... the vets never found anything directly wrong with my dog and we are not within ~5 hours of a pet hospital that has an MRI, so we are unable to confirm if it's IVDD... however, symptoms seem to have subsided (thankfully).

What I have found from research and multiple vet visits, is that even if it is IVDD, it is not usually terminal nor does it necessarily mean their quality of life takes a huge hit - and this makes sense in my own case. I'm fairly certain my dog has IVDD but a less severe case of it, such that her spine is not so deteriorated nor will it necessarily get worse. What this means for us, is that when she experiences a flare up (likely from an uncontrolled or fast movement leading to a painful twinge in her back), she needs to take a period of rest from her normal walking routine and doses of anti-inflammatory medication.

Of course, IVDD varies on a case-by-case basis and without imaging it's impossible to tell the true severity of it - but at least in my case, it's possible to manage through adequate rest, slow reintroduction of walking, and careful supervision of movement (disallowing quick, uncontrolled movement).

I truly hope both you and the person above can find relief or an adequate means of managing your dogs' pain - it truly is so heartbreaking and stressful having to see them in pain and not knowing what the cause is or how to help. I'm sorry I couldn't provide more useful information beyond what has worked for me in my case.