what is the general reason for a lump on the right artery of the neck and long term diahrea?

Hmmm . . . off the top of my head, I can't explain the two.  However, an overactive thyroid (as evidenced by a lump, but not usually over your jugular vein) can cause diarrhea (along with out symptoms, such as diarrhea, tremors, anxiety, fast heart rate, weight loss, sweats, bulging eyes, etc). 

One person's diarrhea is another person's constipation.  Normal bowel movement frequency is anywhere from once daily to once weekly.  The most important detail is that you're not straining regardless of the frequency.  Typically, the more fiber you consume, the more frequent your bowel movements.  Same with regards to fluids & physical activity.

The other important part about diarrhea every day for over a year is whether you've lost any weight, seen any blood, or had antibiotics.  Regardless, given the chronicity of your complaint, I'd suggest that you go see your family physician.

A simple blood test will determine the state of your thyroid.  Simple stool tests can determine the presence of infection.

Good luck!