Hello, Fatigue in the setting of HIV disease can have many contributing and overlapping causes. It was a good idea to check for anemia - apparently this is not a contributing factor in your case. Two weeks of anti-depressants may not be adequate to rule this out as a contributing factor. Having recently tested positive is a major stress. Talking with an HIV knowledgeable counselor or therapist may help determine how you are adjusting to your new diagnosis.
Low testosterone can also be a factor.
Even if this is only slightly low replacement therapy may help. Medication side effects are also a common cause for fatigue. Finally, HIV is, of course, a virus. Viruses are well known to cause fatigue. These are viral illnesses and they certainly cause fatigue along with other symptoms.