Additional information: the past 5 weeks I was under tremendous stress from this event specially it was my first sexual act and worrying about std. For 5 weeks I only masturbated three times and I forced all of them just to see and monitor changes. I used to do it 6 times a week. I am not having erections even the random ones that I used to get a lot.

Thanks 

I can understand why you're nervous, since this is your first sexual encounter -- and it sounds like you may not have had very good education about STIs in school or elsewhere. But the news is good:  you were not at risk for any STI; and your symptoms don't fit with any STIs at all. To your specific questions:

1) There is no STI risk if there is no direct genital-genital, oral-genital, or genital-anal contact. For males, that means no risk if a bare penis does not enter a partner's vagina, rectum, or mouth. Touching, body rubbing, genitals briefly touching, kissing, hand-genital contact, and fingering are risk free.

2) No STI causes such a skin growth. Genital warts come closest, but this doesn't sound like a wart based on your description; and genital warts cannot sppear sooner than 6-8 weeks after exposure. Anything you noticed only 6 days later probably was always present. Also, neither warts nor any other STI can cause changes in skin color such as you describe. Almost certainly your anxieties about this event and your fears of STI are making you more liable to notice minor variations in genital skin that you otherwise wouldn't bother you or you wouldn't even notice. STIs cannot cause changes in libido, masturbation frequency, erectile function, or frequency of erections. These too are psychological symptoms.

See a doctor if you remain concerned about any of this. But I do not recommend any STI testing. You're fine.

I hope this information is helpful. Let me know if anything isn't clear.

HHH, MD