It sounds like it could be a yeast infection. Yeast just happens sometimes, it's perfectly normal and you can get them without having sex, so no worries there. It's an imbalance of the natural bacteria in your vagina. Since you did have a lot of sex though, it could just be from that - sometimes lots of sex leads to yeast. If it's your first one, it's best to go to the doctor just to be sure that's what's going on. Your doctor can prescribe you a pill to treat it, or you can get an over-the-counter treatment. You can also use homoepathic remedies, especially if you start getting them frequently (there's information about treating yeast with yogurt and garlic in the archives, though if you need more info from me I can tell you about that).

The other thing it could easily be is irritation from the spermicide. Spermicidal are really hard on your vagina, and the small amount of spermicide on condoms has been proven fairly pointless anyway (it's not enough to make any significant difference in protection, just enough to irritate your vagina), so I wouldn't use them if I were you.

For now, try wrapping an ice pack in a towel and sleeping with that between your legs. It helped me a *lot* last time I was seriously itchy and burny from a yeast infection.