No, I do not understand that embarrassment and I have no patience with it. You must describe all those details to the dermatologist. Just do it. S/he has heard and seen it all before; your story is nothing compared to others s/he has dealt with on almost a daily basis. Trust me on this.
Stopping after the opening lines: In 30+ years in the STD business, with 6,000+ men attending my STD clinic each year, of whom at least 80% have had genital HPV at least once, I have never seen a case of penile cancer. It is a very rare disease, even in people who have had genital HPV.
To your specific questions:
1) Penile cancer usually takes years to develop. But I can't say whether it sometimes can be as short as a few months. But what you describe doesn't sound at all like penile cancer anyway. I won't try to speculate; you are smart to be seeing a dermatologist.
2) Yes, warts are common in the anal area, including men who have never had any sort of anal sexual contact. But presumably the gastroenterologist saw the bumps when s/he told you that hemorrhoids were not the cause. What did s/he say about them? In any case, have the dermatologist take a look.
3,4) Penile cancer is painless. No STD causes the sort of general genital area pain that you describe. However, genitally focused anxiety definitely can do it. You can learn a lot about this if you google "chronic pelvic pain syndrome"; the Wikipedia article is quite good.
5) No STD or other virus can cause symptoms in less than 24 hours. Whatever you had was caught at least 2-3 days before your symptoms started. It could be just a garden variety cold or flu-like syndrome.
You are overreacting. There is almost no chance you have anything seriously wrong. Keep the derm appointment, but settle down in the meantime.
Good luck--- HHH, MD
Sorry I've started a new thread but I'll be gone once these are answered. My Derm appt is next tuesday and you must understand that I cannot ask these types of questions in such detail because I am too embarrassed.