Has prostate cancer been ruled out?
Patients with prostate cancer have a lower level of lymphocytes, however your percentage being above
15% is within the lower "normal" range.
The drop from 25% to 15.4% is of concern though.
It is possible you also had an allergic reaction to your medication, however, this would explain some of your symptoms, but not the lymphocyte drop.
Best wishes,
Niko