This is not a normal issue with Enzalutamide. Even though he is on Enzalutamide And his PSA may show it’s undetectable, Metastasis can occur and cause issues.

If his PSA is undetectable, then a PSMA pet scan may not show anything, But in cases of large Metastasis it does show up.

In this case, a CT scan may be useful to compare previous to current.

Darolutamide Works very much like Enzalutamide, But has fewer side effects. If they can’t find something wrong with scans, then maybe changing the drug will make a difference.