Robbie, reading through your posts on this thread, you are doing nothing but improving. Mobility wise certainly and looking a bit deeper you are thinking more clearly as well. Then you have an mri and it shows one new lesion. Maybe this was developing even before you started antibiotics. I don't think you have become resistant to doxy, but are just shaken by the scan. Any sort of stress even now can take away a lot of my improvements for a while. Also, you need to keep exercising regularly to keep up your amazing improvements.
If you really wanted to, you could try azithromycin or roxithromycin as a replacement for doxcycline although ideally, if you were following the Stratton/Wheldon protocol you would already be taking this combination. Not too late to start, though: you haven't been taking the stuff for long enough. Read these again and take at least the pdf to show your doctor if necessary:
If you give up now after doing so well, I will be so disappointed.
(Leetz, you are doing very well!)