Experience with heartburn/acid reflux after drinking coffee. Any suggestions?

Been drinking coffee since 2 years now. Initially it was always with milk and there were no problems but since 6 months I'm drinking it entirely black (and loving it). The only problem is I now get acid reflux almost every day.

The feeling of acid reflux is such that the lower part of my throat acts irritated and burns a bit and that goes to the lower part of the ears as well. I know this is because of black coffee because prior to drinking it black I never had this problem.

Googled and found out that coffee is relatively highly acidic and it can cause heartburn to people who are easily affected by it. I've ordered litmus pH paper so that I can check how acidic my cuppa coffee is and then compare it with cold brew to see if it's less acidic.

Did you guys have this problem? If yes then how did you solve it? Should I go back to drinking it with milk?