Several years ago, we took in a very sweet, stray dog who was found wandering down our street. She came to us totally flea-infested. Needless to say, our cat and our other dog and our house also became infested. HARD to get rid of those little things! Anyway, we all had flea bites, but none of us had anything like you describe with the aches and swollen glands, etc. I think you are either very allergic to the flea bites, or maybe you have an unrelated virus. I think you should make an appt. to see your doctor, just to be safe. And I would think your employer would be required by law to provide a safe workplace and should therefore call an exterminator to rid the office of the mice and the fleas.