my armpit area has a slight pain and a tingling sensation

hi, school has just started, i am 14 years old this year. Today when i came back from school, i found the left side of my shoulder aching around the armpit area. i soon found a lump the size of a pea on my armpit. In the middle of the lump there is a red dot, the kind that you normally find when you scratch your skin for a prolong amount of time or the type u get when u pierce the skin with a needle or so (the red dot is very small). my whole arm feels like it is aching and my armpit area has a slight pain and a tingling sensation, it is very painful when i touch it. I am scared it is a form of cancer or is it just a lymph node infection, please help me and thanks in advance
additional notes: i am having my period now, i have been having insomia and only slept about 2-3hours yesterday ( i wonder if the lack of sleep has anything to do with it)
i am not sure when i lump appeared but i only notied it today and the lump (and my left arm) only started to ache today after i came bck frm sch