Sue, teriparatide is know to prevent synovitis and to prevent the degeneration of cartilage in the joints.

Forteo can increase serum uric acid levels in some which could cause crystal depostion in the joints. I've read that sustained levels of high serum calcium can cause calcium deposition in the joints.

Most studies don't credit Forteo with other than mild joint pain during use. There is a retrospective associational Chinese study that concludes that Forteo may cause joint and muscular disorders. https://pubmed.ncbi.nlm.nih.gov/39016171/
More than that though I trust your experience which seems to implicate Forteo. I hope you can get imaging of the most painful joints. It isn't sufficient for a physician to say that you have arthritis. That's just telling you what you've told them. Even if Forteo was the initiating cause, there should be something that could alleviate the pain. I'm glad to hear the fatigue is lifting a little.