Now that you mention the livedo reticularis, I think of spasms even more...because livedo reticularis is actually caused by the spasm of medium sized blood vessels in the skin. Again, an autonomic dysfunction.

Your cardiologist is on the right track with the vasodilator, but should consider nitro just to see first if this is helping the problem, then work on finding a medicine that helps longer periods of the day. If so, then a nitrate (long acting nitro) may be enough. I use cardizem CD and Imdur to keep the spasms under control. It takes time though to find the right dose (slowly), especially if you have orthostatic hypotension.

There are several things you can do to help with gastroparesis. First is to eat small meals vs large ones...also do not eat in the evening so to avoid night discomfort. A true gastroparesis diet avoids raw fruit, raw veggies, nuts, etc....things that are known to be hard to digest. Beano and gas x are helpful to manager gas from lack of GI motility. There are limited medications for gastroparesis, like domperidone. You should try working with your diet without this unless absolutely necessary and/or you have severe problem (gastric empty under 10%). Walk after eating helps to naturally empty stomach and sleeping on a wedge pillow can help also (but best to just avoid eating late). Those with gastroparesis can easily get SIBO (small intestine bacteria overgrowth) from unbalanced flora and back up into the small intestine or stomach. MrsD's suggestions help avoid this. Also avoid lots of sugars/carbs that feed this bacteria. There is also specific antibiotics (only used for GI) that also help if it gets out of control. The best mgmt is to stay on top of your GI health with simple changes in diet & habits that may not seem to do anything right away, but go a long way in the end should you get SIBO or severe gastroparesis.