I understand your agony.This is the problem which most patients face before getting a conclusive tissue diagnosis. Let it be infectious disease or a cancer. The presentation is very confusing. I suggest you to get admitted and get a lymph node biopsy
done which can easily be done under local anaesthesia if it is not deep seated and if it is in the neck in particular. Otherwise Ultrasound/CT scan
guided core needle biopsy is another alternative and a bone marrow
biopsy done. Once the disease is confirmed appropriate treatment can be given.
Please take care of yourself and hope you get good support from your family and friends
Get well soon