Hi Radiant,
Welcome to the forum! We're so glad you found us, although we wish it was because of a different circumstance:) If you haven't already, please read the thread titled, "New To Lyme?...Start Here!" It has very valuable information that will help you through your Lyme journey, including how to prepare detox baths.
I agree with Razzle. Your doctor or his nurse, should have been willing to speak with you especially if you are having posible side effects from this medication. It could also be a herx reaction, which is a die off of bacteria. Once the bacteria die, they release what is called toxins into your body that cause your symptoms to get worse. Try doing a detox bath and see if some of your symptoms subside. If they do, I would say that it is probably a herx.
One possible reason you may have felt better on the first day of taking Doxy is because it has an anti- inflammatory effect, which means that it reduces inflammation in the body.
Here is a great site explaining what a herxheimer(herx) is:
http://www.associatedcontent.com/article/87765/lyme_disease_what_is_a_herxheimer_reaction.html?cat=5
Here is a great link with information on Doxycycline: (A must read!)
http://www.ehow.com/how_2165217_avoid-doxycycline-side-effects.html
Great information on Lyme Disease and dosaging of antibiotics:
http://www.ilads.org/lyme_disease/treatment_guidelines_clearing_ilads.html