Have Low Grade Fever. Had Malaria, Fatigue And No Appetite. Using Doxicycline. Medication?
What is your job profile like? It seems like a chronic ongoing infection that is occurring in you. It does not seem to be malaria to me too.
Doxycycline worked for you. That means to say that there is high chance of rickettsial infestation in you along with leptospirosis, and other tropical illnesses that are vector borne.
To educate you about this, there are specific lab tests available that are expensive and not routinely done. It is usually a clinical diagnosis made by a physician according to patient symptoms and clue.
If I were your treating doctor, I would treat you empirically for the rickettsial diseases with Doxycycline twice daily for 5 to 7 days. Meanwhile, I would advise complete bed rest, plenty of fluids, and keeping your living area free of mosquitoes and other vector.
These diseases are debilitating as they are hard on the joints, and do make you feel fuzzy headed.
Please do write back for further discussion on this. Hope this helps you.