( Please Help ) I hold this red bump on the right side of my chest and it's swollen a bit. ?

I just notice it there a few days ago.
The single symptoms are that the right side of my chest is swollen by a few millimeters , and the bump looks like give or take a few half a centimeter, .
and a few weeks ago, i have a bigger red bump on my left arm, i really dont know if a bug is doing this, or what category of bug. Little red bumps are kind of sturdy to diagnose. It could be a bite, maybe spider... not sure if mosquitos are out and just about in your nouns. Could be a pimple.. Does it hurt? Could be a boil, if so watch for MRSA - two of my daughters have MRSA boils last year.
in-grown tresses?