Wecome to HCM
Un explained weightloss of 8 months along with low grade fever
,generalized wekness warrants urgent attention, I hope you have been examined and investigated simultaneously.
A Low blood count of WBC,RBC and Platelet is called Pancytopaenia along with enlarged Lymph nodes possibilities may be some kind of hematological disorder like Aplastic Anemia
,Mylodysplastic syndromes ,Lymphoid malignancy or Hodgkin lymphoma
,or Atypical Infection
HIV all these must be kept in mind while trying to investigate such case.
Kindly Consult a Haematologist and Surgeon and go for Lymph node excision Biopsy I hope it will give clue to diagnosis.
If required a Bone marrow
Biopsy may be performed
Once cause is known treatment may be planned accordingly.
Best of Luck