Theres a lump under my toddler's armpit. Any parents out there have ever experienced this before?

Hi dear, based on what i have read before. Toodler lump can be due to various reasons such as a cyst, infection or even allergic reaction. However there is more to it. Its best to take him to the doctors to check. I have attached a link for you, hope it helps. http://www.rightdiagnosis.com/symptoms/armpit_lump_in_children/common.htm

thanks