I have what i believe is a hemorrhoid. it's been bleeding moderately for almost three days. having to change boxers and sheets from the bleeding. it doesn't seem to have let up. should i seek care?

Your question answers itself- of course you need to see a MD. It may or may not be a hemorrhoid that is bleeding. The bleeding , if it continues, can lead to low blood levels. (anemia) See a MD soon.

It would be unusual, still possible for a hemorrhoid to bleed between bowel movements. Seeing a doc will help in clarifying the diagnosis and most important stopping the bleeding that appears to be significant.