Hi Deb,
Sorry to hear about your problems, I can understand your worry and how scary it can be. Unfortunatly the best way for them to find out what it is is to get in there and have a good luck, If it is an infection the op that i would recommend is the two stage revision as it carries a 90% success rate. I was diagnosed with an infection over a year ago now and had an operation to remove all of the metal and cement, i then had a antibiotic loaded spacer put in to 'fill the gap' as it were. In my case the spacer worked just as well as a normal hip for me, could weight bare and was mobile. This stayed in for 11 months until all the aspirations came back clear. I think the WB cell count needs to be backed up by a nuclear bone scan to see where all the cells are going.
I hope that you get some results soon and if you want to ask anything feel free to send me a message.
Best wishes
Jak