I would get the doxy a.s.a.p to be on the safe side. This is what I did a year ago when I had a deer tick attached to my thigh. 10 days later the small red mark spread to a long rectangular red blotch...not a bullesye. Then I developed all kinds of weird symptoms, so I went right to the er. Later I sought out a LLMD in my area. Depending on what dr. you use will decide what antibiotic to use. I was tested positive down the road which i guess was a lucky reading. Good luck to you.
6-8 weeks of doxycyline seems to be the most common approach in the LLMD literature, and I would suggest taking a good probiotic opposite it to mitigate the effect on the good gut bacteria if possible. By opposite I mean if you take the doxy morning and evening, take a probiotic noon and bedtime.
I am just over a year into my personal battle with Lyme disease (having had undiagnosed *severe* symptoms for 5 years prior to that, and minor symptoms much longer) and it is NOT worth the risk. The tests for Lyme are unreliable and by the time you test positive, if you ever do, you could be in trouble. Find a doctor who will prescribe the 6-8 weeks of doxy!!!