one time use

I may have contracted Lyme's again. I had Lyme's disease over the summer of 2007, with a face palsy. In October I was clear. Yesterday I found a dead tick on my thigh, which I pulled out and felt very arthritic during the day. Today I feel less stiff but a bad headache and vision migraine. All of these were symptoms of the Lyme's I had in the summer. My doctor has recommended I take just 2 100mg Doxycycline as a prophylactic measure. What do you think? Concerned...