You need to see a doctor. It could just be a virus, but very possible you could have an infection going on in your body. Lymph nodes swell and become present when trying to fight off a virus or infection in your body. See a doctor and have a CBC done. He also might need to drain or biopsy a lymph node to check for infection.
Hello~Sometimes, recurring lymph nodes can be signs of a hidden infection ( This can increase the number of white blood cells, which multiply in response to stimulation with a foreign substance (antigen) ) or even an allergy as our bodies are trying to keep our immune system well.
As to not be allergic to the deodorant, folks bodies can change sometimes and what they were not allergic to in the past, they can be allergic to now. I would try switching brands and if possible, use one that is unscented, sometimes the perfume in them can cause this problem.
If this keeps up and you notice pain with them, I would definitely see a doctor about it, it is always better to be safe than sorry.