Dear leishylou: We all have quite a bit of variability in our heart rates over a 24 hour period. When your heart rate occasionally increases to 98 beats per minute, that will feel “fast” to you, but it is not fast enough to suggest any arrhythmia of the heart beat. Usually, abnormal arrhythmias that occur at rest are associated with heart rates that are over 150-180 beats per minute. It is great that you have taken your pulse rate, as this is very helpful information for your doctor to have. It is also important to make sure that you are drinking sufficient fluids each day (32-48 ounces), or else your heart rate may increase.
As far as the brief, stabbing chest discomfort that you are experiencing, it is important to know several things: is it brought on by exercise or does it occurs at rest? Does it worsen with movement or taking deep breaths? Is it very brief or long lasting? Is there anything that you can do to make it better? How long has it been going on? Do you have asthma? Is there any history of heart problems in your family? Most chest pain in young people is NOT cardiac in origin; mostly it is either musculoskeletal or related to the lining of the chest and lungs. Occasionally it can be of gastro-intestinal origin, such as acid reflux.
Finally, if you are experiencing shortness of breath as well, or a change in your exercise ability, it is important to see your primary doctor soon, and review all these symptoms with him/her. They may want to get some testing, such as an EKG and chest x-ray.