Wbc went from 2.6-1.7, absolute neutrophil 0.6-0.4 in 6 months. Monocytes and lymphocytes are still high. Could this be a type of leukemia?

Leukemia? Might be leukemia, myelodysplasia, or temporary drug side effect. A good evaluation done by a qualified physician should be helpful.
Concerning. With this drop in neutrophils into a risky zone, you need to be under the care of a competent hematologist -- in fact, you should have been referred when an absolute count of 600 was discovered. This would be a great time to stop taking the Ibuprofen -- allergy might be the cause -- and try to stop smoking as well.