What Causes Small Red Spots On Inner Thighs,wrists And Upper Arm?

I developed small red spots on my inner thighs and my wrists. They have spread to my upper arm (just one or two). I got a steroid cream and applied it for three days but it got worse. I bought antihistamine tabs today, but just now have noticed I have two red spots (itchy) on my penis. The irratation gets unbearably itchy at night...Is it hives, bed bugs, scabies or possibly an STI? Thank you