What Causes Extreme Fatigue Along With Shortness Of Breath And Dizziness?

I am a 47-year-old female with Ehlers-Danlos syndrome and aortic root dilation with aortic wall thinning. In the last year, I have had an array of symptoms that have gradually gotten worse. First, I had extreme fatigue. So extreme that I have to sit on a stool by the stove to cook a simple meal. Then, came severe shortness of breath and dizziness when I m up for approximately thirty seconds. Now, I have tachycardia (verified on 30-day Holter) added to this mix.The only relief to this is to bend down, hold my head down, and wait for the symptoms to pass. A nurse in my support group mentioned POTS. My question is this - who d be better to see for diagnosis - a neurologist or a cardiologist? My research lists both. I am located in Eastern North Carolina, USA. Thank you in advance for you time and assistance with this matter.