What could cause the lymph nodes in my neck and groin to be swollen for a month and little red bumps popping up everywhere?

Monitoring Centers. Lymphatic system absorbs/carries things too big to go into the arteries/veins like bacteria eaten by white cells/digested food. Lymph nodes "taste" the lymph everywhere for bad stuff 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.
HMM. It could be many things from infectious to metabolic...It definitely needs to be evaluated soon by a physician...See your family doc soon..Especially since you say that it is getting worse..