What's a good way to check if my lymph node is swollen in my neck?

You will feel a bump: Neck nodes can be easily felt as a knot or lump with your own hands if use the tips of the fingers. You can feel round srructures like a small ball. It is difficult to feel the nodes if they are smaller than one centimeter.

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.