I've been on doxycycline since Monday and I am still running a fever (102) and chills. How long should this fever last? I have been in bed all week, drinking a lot of water

Viral? Your problem sounds like viral which does not respond to antibiotics. In fact, your nausea may be from the doxycycline especially if you do not take it with food. As a rule of thumb, viral infection seldom lasts more than 10 days. If you are getting worse or your fever goes beyond 103, you need to contact your doctor again to find out what else may be happening.