Disregard the above post, oral sex is not a risk for HIV, there have been a few stories about people claiming to have tested positive with their "only" risk being oral sex, but in every scenario they end up remembering that that actually had a another risk such as unprotected anal or vaginal sex. No need to test.
"Although some experts believe mouth-to-penile transmission never occurs, most agree it happens but very rarely. It is so rare that 99% of the people who worry about it should just get a life and forget about it."