if the only symptom is tailbone pain...and this wasn't one of your original symptoms - I wonder if it is from the lyme.
You could ask for minocycline and pulse tinidazole two or three days a week (for cyst form)
Minocycline is 100 mg twice daily and tinidazole 500 mg twice daily two or three days/week.
Hopefully if you do antibiotics you will have a response soon...and you'll know if you're on the right track (either a herx...or you'll feel relief in the tailbone pain)
You can subscribe to LLMD MR TreatLyme online book - there are many combinations of antibiotics there:
www.treatlyme.netI think it's only $4.99 per month...so you could subscribe for a month and write down the combinations.
With only that one symptom...maybe consider doing an herbal protocol instead? You can buy the herbs online.
(since it's not clear that the symptom is from Lyme)