Swollen small nodes on my neck for which two ultrasounds were conducted in 2013. I still feel them two years later while I haven't noticed a difference in size. Should I be concerned? Internist isn't.

Not to worry. Neck nodes are of concern only if they are growing in size and get to a size of > 1CM. It looks like your nodes are smaller and not growing in size. So you need not worry. Just check their size once every month or two. Good luck.