Questions or concerns about your eyes are best answered by an ophthalmologist. An eye specialist
can take a more thorough history and examine your eye to give you more information about what might be causing your symptoms. Unlike primary care physicians
who can also examine the eye in a general sense, eye specialists will have specialized equipment in their offices that will allow them to see the eye in much greater detail.
Overall it sounds as though you could possible have an infection in the upper part of your eyelid. You could also have a small cyst or stye or other type of swelling that becomes more pronounced in the morning. In addition, in order to keep your eyes from drying out, your body is constantly secreting a thin film of lubricant to keep your eyes moist. Sometime the eye or the area around the eye can swell when the normal drainage pathways for the fluid lubricating the eye are disrupted.
An eye specialist is the best person to help you understand what is causing this swelling. In the meantime you can definitely continue with your healthy eating and exercise habits as these are unlikely to have caused the changes in your eye (the timing is probably a coincidence) and healthy lifestyle choices are of great benefit to your overall health.