Neulastin problem

Hi all I was wondering if anyone has had issues with neulastin injections? After my 1st chemo treatment my white blood cell count dropped to zero so it was recommended for future treatments that I inject neulastin the day after chemo to stimulate my bone marrow to produce white blood cells. I've had no problems on my next three treatments until last weekend, 9 days after my 5th chemo. I was particularly unwell on Saturday, nausea, vomiting, the runs and general malaise. I developed a lump the size of a fifty cent piece under my arm on the side of my lumpectomy as well as pain in the shoulder and upper arm. I ended up being admitted to hospital overnight and being put on iv antibiotics. My white blood count was really high. I saw the oncologist yesterday and they think I have had a reaction to the neulastin. Seems strange that I've used it 3 times and not had a problem until this 4th time. Was wondering if like chemo, that maybe it is a cumulative affect? Due for chemo next week but don't know if I will have to have it again as my white blood cell count hasn't dropped. My inflammatory markers are low and this is why they don't think I have an infection. I'll be very interested to hear if anyone else has had similar issues. Thanks, Karen