104 is not bad. Stress/anxiety, caffeine, or activity can bring it up to that level very easily. Usually people are nervous while getting an ekg too so I wouldn't worry about 104.
What is your blood pressure like? Buy a home blood pressure machine and take it every day to see what your average blood pressure is. Whenever you feel like you are going to pass out, sit or lay down (important! you don't want to faint and hit your head on the way down.) and take your blood pressure then too (or ask a nearby family member to do it). Heat such as from a hot bath can lower blood pressure as it dilates the blood vessels and therefore lowers the pressure, especially if you have underlying heart issues. I used to work on a heart floor of a hospital and we'd be required to stay with a patient during their first time showering to ensure they were not susceptible to passing out because of the heat.
So give your doc a call to make sure the ekg showed nothing else besides tachycardia (the 104 heart rate), and start monitoring that blood pressure.
Oh, and also some people have orthostatic hypotension, which is where they get light headed and dizzy if they sit up too quick or stand up too quick. This is because the body needs additional time to adjust the blood pressure. (Think about it this way, if you are laying down the heart doesn't need to work too hard to push the blood horizontally, but when you sit up suddenly it has to push blood vertically to your head, and if it doesn't adjust that quick enough to send the proper supply you will feel the effects). So for this, change positions slowly to give your body time to adjust. This will happen to everyone here and there, but if this happens very frequently, see your doc for a potential heart problem.
