Did you spray the product under/around your arms? Sounds like an allergic reaction to this product. I would assume you stop using it and monitor the sites involved. If it continues to spread, you will need to see a physician. You can also try taking an over the counter allergy medication to see if they respond to that, i.e. benadryl.
If you noticed all of this after using the product; it is the product, NOT cancer.
I don't now much about it....but it's possible it might just be enlarged lymph nodes. I also have one on my jaw/neck that swells to about the size of a quarter every once in a while. They can be painful because they often press on nerves around them (such as mine), but are otherwise not dangerous. If you could possibly get a doctor's appointment that would be a good idea. They can tell you if they can be eventually removed or if you just have to deal with them (they do shrink back to a small size a lot of the time).
My brother had cancer and had a lump on his neck (the first symptom, but i've heard that the lumps that are cancerous don't hurt when you touch them. I don't now how true this is though.
But it might also be serious. Keep on eye them and keep us all posted. Also, are there any other symptoms you have noticed? (fatigue, other pain, etc?)
Peace, Audrey