Hi mcjane. Are you being treated by a Lyme doctor?
From what I understand, 200 mg of Doxy is not strong enough for Lyme. I believe the recommended dose is 300-600 mg daily with 400 mg daily often prescribed. If you have not done so, I recommend reading Dr. Joseph Burrascano's 2008 Diagnostic Hints and Treatment Guidelines For Lyme and Other Tick Borne Illnesses at http://www.ilads.org/lyme_disease/B_guidelines_12_17_08.pdf He is one of the top Lyme doctors in the country, and many Lyme doctors follow his protocols. He discusses antibiotics and doses starting on page 18.
It sounds like your infection is early which is good. Early infections are the easiest to cure. Getting the proper treatment now may reduce the chance of long-term complications.
Flagyl or a similar med treats the cyst form of Lyme which typically occurs later in the infection.
Are you aware of the Jarisch-Herxheimer Reaction (herx)? Often, when people who have Lyme take antibiotics their symptoms get worse or they get new ones. When the antibiotics kill the bacteria, toxins are released making them feel worse. It can be scary, but it is a good sign the antibiotics are working. During treatment it is a good idea to document your symptoms daily. One way to do this is to list the main symptoms you have each day with a numerical rating of their severity from 1-10. Over time when you review this, you can see when your herxes occur and how you are responding to the meds.
It is important to learn as much as possible. I also recommend the books "Everything You Need To Know about Lyme Disease Second Edition" by Karen Vanderhoof-Forschner and "The Lyme Disease Solution" by Kenneth B. Singleton M.D.