I am not wanting to start an argument with you, but many people have termperatures above 98.6 that is their baseline. I have personally had 3 patients whose baselines were above that "standard" number.
99.4 is never a normal temp.
Chronic Fatigue Syndrome and Fibromyalgia..............neither are easy to diagnose and some physicians dont't even recognize these conditions especially Fibro.
Spinal tap or a Lumbar puncture may be a test that might reveal something.
Have you seen any specialists?
This temperature elevation could well be your normal body temp. Mine personally is much lower than 98.6 as is believed to be normal. What is it you have been doing when you check your daily temperature. If you have been active, instead of at rest, perhaps it is relevant to that? Also, just because you are on medication for depression or anxiety, doesn't mean it's being treated effectively....you may need a different medication, a higher dosage, or another medication entirely. Has anyone ruled out chronic fatigue syndrome in you or fibromyalgia? They are two disorders that need looking into. Good luck!