Cyst? on private area? Help please. Pics

No ma'am, do NOT give antibiotics.  You couldn't know if it was gram positive or negative, and you could make it difficult for a vet TO tell what was wrong (if they had to draw blood). 
 
Honestly this is a need for a vet visit TOMORROW.  Don't worry about how long it's been there -- just go.  Any sort of 'cyst' or bump on the prepuce area (and that's anywhere near his willie) is dangerous.  Don't wait.  Just go to the vet tomorrow. 
 
Now the vet may say "let's see how it developes or changes" but that's HIS call. 
 
What I'm telling you is that there is specific types of cancer that can come out there, and it is virulent. 
 
Leave it alone and don't mess with it.  Because that can cause it to grow, and that's one of those things you don't WANT to irritate.
 
It's a good call to catch it... but unfortunately that's where my Muffin's first mast cell tumor appeared and the darned thing doubled in size in a week.  And it's a tough spot for surgery. 
 
Now hopefully the vet will say it's nothing, but I wish *I* had known it was a dangerous area.  Took me by surprise.

okay, I'm making an appointment today.
I hope it's nothing serious, I've been sick about it all night.
 

I hope it's 'nothing' too -- but I'd rather yank your chain and have you find out it's nothing, than *not* and have it wind up too late.  Not only is it fast-growing, when they do surgery they can't get 'clear margins' because there's no extra tissue there. 
 
IN honesty I'll be thinking (and sending good thots and prayers) all day -- I don't think anything on the planet gives you quite the same 'sick feeling' in your stomach as this.  We did ultimately catch Muffin's in time, but I'm glad you'll find out something today.  *hugs*

His appointment is tomorrow at 6:30. It didn't look anybigger this morning. I was sick and almost frantic about it last night when I found it, and now I just feel ill everytime I think about it.
I just worry how long it's been there...and how long I might have mistaken it as his private poking out. I hope he hasn't been in anykindof pain over this, and I hope that it's nothing serious.
It just makes me so upset even thinking about it....

I totally understand.  I got so freaked with Muffin's I started him on a cancer diet before I went to the vet the first time. 
 
All we can take refuge in is the fact that it's love that makes us so crazy.  But try not to worry (which I realize is like telling the sun not to set) ... but seriously ... it will only freak HIM out.  So deep breath, and realize you did a GOOD thing by finding it when you did, and likely you found it quicker than you thot you did. 
 
When I found Muffin's it was FOXY who found it.  I noticed him sniffing at Reno's 'willie' and I said to him 2-3 times "WILL you leave your brother A-LONE??" Please??"
 
And the last time Foxy just looked over at me as if to say "Will YOU please PUH-LEESE look at this CLOSER?? I am trying HARD to tell you something here MOM!!!"
 
Many times in the future that dog told me about another dog with cancer.  And dang but he was right.  I used to tell David that if he ever sniffed ME that way I was gonna worry.
 
One time we were at the vet (the holistic vet) and Foxy was sniffin all over this old dog named Capone. And Foxy turned around and came straight TO ME and then looked up at the door to the vet's office and then back to me ... and I said "Foxy, SHE KNOWS.  That's why Capone is here ... Dr. D. KNOWS about it."
 
Foxy laid down and sighed. 
 
(Foxy's the almost 19 year old I lost last week -- *sigh*  Can you tell I miss him??)

What did the vet say?  I hope everything is okay.