Thank you for the additional information.
There are many different possible causes of a racing heart, shortness of breath, and slight dizziness, and it is impossible to determine the cause without a proper evaluation.
Although this is not always from a heart problem, this is the first concern. This could be related to a primary abnormal heart rhythm that is secondarily causing the shortness of breath. Some of these abnormal heart rhythms are more serious, while others are less serious. Abnormal heart rhythms are most often due to an alteration in the electrical fibers in the heart, but can occur secondary to other heart disease.
It is also true that the more serious abnormal heart rhythms would be more likely to cause a greater change in blood pressure or pulse, which is why I ask if these could be checked during an episode.
Some people also can get a racing heart from lung disease, because a drop in oxygen level can cause the heart rate to increase, but these people also usually have some episodes of lesser severity in which they are having shortness of breath without heart racing, so would be less likely in your case.
It is also possible that the symptoms could be due to a systemic condition, such as thyroid disease or an electrolyte abnormality.
It is also important to note that these symptoms can occur from relatively benign conditions. For example, it is common for someone to get a racing heart and shortness of breath from anxiety or panic attacks. While someone can feel absolutely miserable during these episodes, there are no serious repercussions that can occur, which is why they are referred to as being relatively benign.
If you are unable to monitor blood pressure and pulse during these episodes, it would be more important that you seek further evaluation relatively quickly, because we would rather not delay evaluation if there are significant changes that occur during these episodes.
So, the best next step would be for you to be seen soon for a proper evaluation.
If I can provide any additional information, please let me know.