Hi
Welcome to the MedHelp forum!
Chronic sinusitis can be the cause of persisting fever. Recurrent or chronic fever is seen in tuberculosis, SLE, rheumatoid arthritis, Polyarteritis nodosa (PAN) and other auto immune disorders, UTI, drug fever, sinusitis, glandular fever, otitis media, IBS, HIV, STDs, endocarditis, parasitic infestations, fungal infections, lymphomas and other cancers etc.
In women, even polycystic ovary, menopause, PID (pelvic inflammatory disease) should be investigated for. Dehydration is a frequent cause of low grade fever with malaise. So drink plenty of fluids and see.
Evening rise in temperature is generally due to anemia, diabetes, hypothyroid states, overwork, stress and fatigue. It is also seen in diseases like tuberculosis.
Since your stomach too feels queasy, there is a chance that you have inflammation of the bowels as seen in IBS, colitis or maybe even gluten or lactose intolerance. Discuss this with your doctor and try and get investigated.
Most labs have a fever panel to rule out most diseases that can cause persistent low grade fever.
You need a comprehensive investigation taking all these points in consideration. It is difficult to comment beyond this without examining. Please discuss this with your doctor and get yourself investigated accordingly. Do let me know if there is any thing else you want to know. Take care!
Have you been tested for mononucleosis, CMV, or chronic fatigue syndrome? See PM for more info.