I can feel my heartbeats and mild upset stomach after I drank coffee, I am just beginning to drink coffee, is this normal and goes away with time?

May or may not. Some people are very sensitive to the effects of caffeine, and I have had patients who get anxiety attacks with a single cup of coffee, and had one patient who got svt (a very rapid heart rate) with a single serving. Many people cannot sleep the next night with one cup of coffee in the morning. If you are that sensitive, don't use as much caffeine. Nobody "needs" it and in excess it can be harmful.