Several bug bite on back just behind shoulder. large swollen lymph node on top of collar bone. bites look to be better though. cause?

Not always bugs!: Several causes for "bug bites." detailed history (how, when, who else) and exam (what the lesion looks like, and what the rest of you looks like) is often needed to get to the correct answer. The most important thing to keep in mind, however, is that many if not most unknown "bug bites" turn out not to be bug bites. Bugs are often blamed incorrectly. Finding the bug on body or home is best clue!

Monitoring Centers: Lymphatic system absorbs/carries things too big to go into the arteries/veins like bacteria eaten by white cells and digested food. Lymph nodes "taste" the lymph for anything bad like bacteria/viruses/cancers, etc. When it detects a problem, it alerts the immune system and your body reacts. They enlarge in response to the inflammation they create when they react. They shrink when all is well.