my daughter is 15 today had a spell she got got really tired all of a sudden and then  her heart started beating heavy she said it wasnt fast but just felt like it was beating harder than normal it lasted about 5min she is taking to med. meloxicam 7.5 and suladizine 500mg. she feels normal now .
The good news is that at age 15, an uncomfortable awareness of the heartbeat (palpitation) is rarely life-threatening. However, there are several disturbances of rhythm and other problems that can be bothersome. One of the most common sources of the symptoms that you described is single extra heart beats in between normal heart beats. While not dangerous, these can make you feel somewhat odd and tired. They usually respond with no need for treatment. In your daughters case, the use of meloxicam and sulfadiazine suggest an underlying medical problem and relationship with a physician. Be sure to discuss the symptoms that you describe and this response with her physician.