Hi there. No need to panic and think anything like cancer. :))) We have a lymph system and lymph nodes in that area. When someone has recently been sick or fighting being sick where the immune system is involved, lymph nodes become activated and can grow in size temporarily. When this happens to me, it's usually one in one arm pit or one in my neck and it lasts for a couple of months after illness. It's common. I had this when ill and I also had this when I got a vaccination recently. I would tell your mom and yes, see your doctor to make sure all is well. good luck
I could be a mole growing(I know that sounds gross) but yes I would definitely see a doctor just to make sure it's not cancer. Hope this helps
Defiantly see your doctor. Lumps in the armpit area can be a sign of many different cancers like breast or hodgcins/nonhodgecins. Your doctor may look at it and tell you it is nothing to worry about but is better to be safe than sorry