It's a really hard call for any of us to tell you what you should be doing. We aren't doctors. Also, I don't believe anyone should ignore any heart symptoms! These infections can do quite a bit of damage to a heart sometimes. I've been lucky in that, even though I went 36 years without treatment, I've not developed any heart issues.
Have you been to Buhner's site? There's a forum for those using his protocol, so you could look for your answers there as well. More information is always better with these infections. Here's a link to his site for you:
planetthrive.com/2009/08/buhner-healing-lyme/ Until you find your answers as to what's going on, I would venture to guess that quite possibly you are taking too large of a dose for your body. Each of us is quite different in what our bodies can tolerate. Maybe try starting off on a much lower dose and build up slowly over several days to several weeks, depending on how fast your body adjust to the medications.
As an example of building up slowly, it took me three weeks to be able to build up to and tolerate the herb I took for my Bartonella infection. Just listen to your body very carefully, go to Buhner's site and read what others are saying, and if you don't have a Holistic practitioner to follow you along, may I suggest, heavily, that you get one? They can be absolutely invaluable when you are trying to figure out what's going on with your body!!