Brief Answer:
heart failure?

Detailed Answer:
Hello,

it sounds like a heart problem. Getting dizzy and sweating when standing usually means a sudden drop in blood pressure (orthostatic hypotension). Getting winded after walking a short distance usually means that the oxygen delivered to your tissues is not enough. Disorders that comprise both symptoms-mechanisms include the following:
- heart failure
- blood loss with severe anemia
- pulmonary embolism
- severe sepsis
- side effects (antihypertensives like beta blockers or others).
Other disorders are also possible including combinations of disorders. For example, a patient with COPD may be in an endless struggle to catch his breath, particularly when engaging in physical activities. Such a patient may present with orthostatic hypotension for many reasons including drug treatment.

Your primary care physician should initiate the investigation. I usually start with a clinical examination to identify signs of various disorders. When the clinical examination is not very helpful, I proceed with lab tests and perhaps with tests targeted to the aforementioned disorders (like a heart echo).

I hope I've answered your question. Please let me know if you need further assistance.

Kind Regards,
Dr Panagiotis Zografakis
Internal Medicine Specialist

---