On Saturday, I got these red spots (thousands of them) on my left arm and on my chest near the collar bone area. I have not been injured and there s no reason I can come up with as to the cause of this rash(?). The skin is still smooth. I am certain it is Petechia. However, what would cause this? I m a 44 y/o woman. I deal with chronic pain caused by spinal arthritis , degenerative disc disease , bulging and herniated discs, etc.