Since you had inadequate treatment the first time around, you are dealing with a relapse - this is quite common unfortunately.
If you feel your doctor is exceptional in listening to their patients, you could try explaining that the standards they are treating by have been removed from the NGC (National Guidelines Clearinghouse) and the ILADS treatment standards are now the currently recommended treatment guidelines. Here is a link to them:
www.ilads.org/lyme/treatment-guideline.php Neither Doxy at 200 mgs a day, or the 21 day treatment is sufficient for these infections when more than just the bulls eye rash is present. Combination therapy is the only way to beat a bacteria that can change it's outer surface protein many times, and find it's way into tissues, bones and the brain.
As PeteZa said though, not many doctors like to hear this from their patients, so tread lightly. It's best to use a LLMD to get the antibiotics (abx) that you will need, or use alternative means to heal. If you need to find one, we may be able to help.