How do birth control pills work?

I've just had my first condom break ever. I'm on the pill, so I'm not worried about pregnancy, but a couple of days afterwards I had yeast infection-like symptoms — no unusual discharge, just itching. If I pick up some over-the-counter yeast infection medication and the symptoms go away, would I be safe to assume that was the problem? Or should I definitely go in for an STI check?

I've been on birth control pills for eight years and I'm thinking about trying a few months off them. They were prescribed when I was pretty young because of very irregular periods. I also was involved in a monogamous relationship for a number of years, so they were convenient. Now I have no steady partner, and am really curious to see how I feel without taking these pills. Would it be ok to go off them at the end of my pill pack or should I consult someone at health services first? If I go off for a few months and my periods are as horrendous as they were when I was younger, would it be safe to start up again on my own (I usually just see someone once per year for pill checks)?

1) I recently had intercourse with a sheep at a friend's house. He is a sheeprancher and one day he was talking about how good it was. He left town for a few days and asked me to feed his animals. I took the chance and gave it a try. The strange thing is that I enjoyed it more than having sex with my girlfriend. When I was a young lad I was molested by a female babysitter. I was wondering if you may think that the earlier incident in my life has affected my sexuality. I liked it so much that I want to do it again, but I am worried that I may contract a STD from the ewe. I have heard that you can.

Could you please help me?

2) I have read about men and women having sex with animals, e.g., dogs (Women on Top by Nancy Friday, Simon & Schuster, 1991). Apart from it being against the law (I think), are there medical reasons why this is not a good idea? For example, are there STDs that can be passed from animals to humans? Are there immunological consequences from depositing sperm into the vagina of another species? Is this kind of sex common?

Is there any data indicating that recurrences of genital herpes occur more often during the winter? That seems to be the case with me.