If you've had full blood tests and all is normal then your case is unusual. Of course people have pain from time to time however yours is perhaps progressing. Shame you missed that original apt as illness is not usually something that stops people from attending a hospital apt, especially when there are long waiting lists.

I'd suggest you stick with the GP as the main manager of your case and they can refer out to others as required. You could have a bone scan to see if there's any increased activity anywhere that might account for your discomfort. It that is clear then you could take it from there. I would think the orthopaedic consult is a waste of time unless that order and Wikipedia reference-linkMRI of the Lumbar spine.

For now it could be anything causing your symptoms.