Yes, if you had unprotected sex, you will need to be tested for HIV at the appropriate time, which is 28 days after if you use a 4th generation Duo test. It's a good sign she tested negative but her window period for any sexual exposures she's had come into play. And it's also something to note that a one time exposure that is unprotected is low transmission risk of less than 2 percent. So, you don't need to be overly worried, but test none the less.
the red spots could be yeast transferred to you by the way. That can transfer. I would say that you also need to be tested for std's with an unprotected vaginal exposure. But yes, it could also be balanitis.
Unprotected sex with an individual of an unknown sero-status warrants HIV testing. If you are here suspecting HIV infection, you can test at 28 days with a IV / V generation HIV test.
For information on other STIs or men's health please post in relevant forum, use the search function at the top right hand side of this website.
Was the vaginal protected?