Can you have lyme or malaria for over a decade, without being diag right?

Yes: I've never seen a case of malaria and most docs in the us have not either, so it might be tricky to diagnose. It is extremely common to have lyme disease for many years before diagnosis. Many docs don't have lyme on their radar, about half who have it don't recall a tick bite and as "the great imitator" it can present with a wide variety of symptoms; standard tests are often inaccurate as well.

Yes, but: For malaria, blood smears, especially during attacks should provide diagnosis. For lyme, dna, not elisa antibody testing will show the specific combination of 'markers' if present.