Yes, condoms during oral sex ('head') is needed to protect both you and your partner from STD's.
You can't get pregnant from swallowing semen, but this puts you at a serious risk for STD's. Condoms are a must if you wish to prevent this.
You can get pregnant on your period. Unless you've been charting your cycles for 6 months or more and have regular cycles, it's hard to really say when you're ovulating (and thus, when you're likely or not likely to get pregnant).
Articles to check out ;
A Quickie STD/STI Risk Assessment
What's The Risk? - Five Easy Pregnancy Risk Assessment Flow Charts
Safe, Sound & Sexy - A Safer Sex How-To
[This message has been edited by LilBlueSmurf (edited 11-16-2004).]