Greetings! I am glad the initial exam was good. Since there is heartburn a person might see a cardiologist to look at the valves of the heart, a general practitioner to point a person to the right specialist or a stomach specialist in case it is that. Of course if those were negative in those areas a couple of others to try might be the pulmonologist in case it is in the lungs and the rheumatologist, in case it is bone or muscle!
A big drink of water might be useful for heartburn for some people if a large meal has not been recently eaten. If a meal was recently eaten I would wait a bit and drink water a bit at a time until better.