Totally agree with Mojo -- get your docs to talk directly to each other -- they are the ones to sort out what to do.
The problem may be that nonLyme docs don't think Lyme is a big deal and a few weeks of antibiotics and you're good to go ... so that may be where your PCP is coming from.
Both docs need, in my untrained opinion, to get on the same page and not just be whacking you over the head with conflicting directions. Hang in there --
Do you have an LLMD? I would ask him or her, they may switch your Lyme meds temporarily if they aren't a good match for what the PCP wants to give you or ask your PCP to talk to the LLMD and work together on it. I worked for doctors in another life and that was done often. Good luck.