Bella37,
Prolonged fevers can have many causes.
One study found that 28% of MDS patients reported fevers affecting their quality of life.
If you search these forums for "fever" you'll find a number of discussion threads about other patients with ongoing fever, including ones named
high grade fever for last one and half month and
Worried about fever.
Presumably your dad's doctors looked for signs of an infection, since MDS patient who are neutropenic can be subject to opportunistic infections. Fevers can also result from medications, nutritional issues, alcohol and drug use, disease treatment, and in the case of MDS can supposedly result from the disease itself. Unexplained fevers sometimes disappear as mysteriously as they appear. Is your dad under active treatment for his MDS?
Without knowing the cause of a fever, doctors may choose to prescribe antibiotics and/or watch for or test for other symptoms. I think it's best to follow your doctors lead, since they know your health conditions best.