What are the symptoms along with fever do you have cold and cough or throat problems, or any urine infection or stomach infection.
Firstly we will have to locate the seat of infection..
Also I would recommend you to get all the tests done if done kindly upload your reports.
I would recommend you to go for Homoeopathic treatment if your problem persists coz homoeopathy is very effective for such kind of problems where you are not able to locate the cause .
This is because in homeopathy we treat the whole system so regardless if what disease u have we will still be able treat it Homoeopathically.