What kinds of diseases can cause shortness of breath, besides heart related and blood clot issues?

Many. Shortness of breath (sob) can be a symptom of many conditions other than heart and blood clot issues. Pulmonary conditions are a major example, ...Asthma, reactive airway disease, copd, bronchitis, pneumonia, etc, anxiety can even cause sob. If you're sob, see a dr. For an eval and work up. (if you smoke, stop). Good luck.