Ethosuximide Side Effect??

My 6 year old son was started on 4ml a day of ethosuximide on Tuesday, September 29th.  Saturday, October 3rd he developed a fever and a cough; his fever reached a high of 103.4 on Sunday.  I called his neurologist office and the on call physician said he didn't think that he was having an allergic reaction that it was probably due to the cough.  I tried to explain that my concern wasn't an allergic reaction but a drop in the white blood cells, but he just kept interrupting me and said it wasn't the medicine.  I took him to our local urgent care and the PA said his right ear was a little pink and she saw some fluid, she gave him a prescription of z-pak.  I brought up my concern about the medication and the low blood count possibilty.  She asked if his neuro did a base line lab draw and I told her no . . . she seemed a little taken back by that but said if his neuro didn't seem concerned to draw a base line that she was confident that the fever was due to the ear infection. 

Over night his fever reached 103.4 again and even after giving Motrin it only went down to 102.  He awoke this morning with no fever and my mother who takes care of him during that day just called and said his temp went back up to 101.2.  I have this nawing feeling in my stomach that this fever is not due to his ear, especially since he wasn't complaining and the PA said it was a little pink.  Has anyone had any experience with the low white blood count and etho?  I called the neuro's office and they don't return calls until the end of the day.