Your symptoms are concerning. There are many possible causes, some of which are serious and some of which are minor. I would recommend that you discuss this with your primary care doctor
. If stumped, it may be worthwhile seeing an Infectious Disease specialist
. He or she may be able to further guide you.
There are three broad categories for cyclic fever
. The first and most common is infectious. There are a few infections that can cause this. Some of the notable ones are malaria, tuberculosis (or TB) and brucellosis. That being said, many other are possible like and abscess. Some people, if having gone to the right places and without prophylaxis might suggest you treat yourself for malaria despite a negative test as the test isn't always perfect. At a minimum, a repeat test might be warranted, preferably while you are having the fever.
The two other broad categories are rheumatologic and oncologic. Rheumatologic refers to autoimmune disease like lupus or scleroderma. Normally there are other localizing symptoms that would point to one of these. Oncologic refers to a cancer, which is a rare cause. Normally, this fever can be caused by a leukemia or a lymphoma, but other cancers are possible.
Talk to your doctor. Good luck!