I will say that you are at NO risk of getting an std from her blood, unless she is HIV/
AIDs positive. Unless she had a break out of any types of sores, I wouldn't worry about stds. More than likely you are just freaking yourself out OR coming down with the flu that everyone else has. Just remember; don't go down on them unless you KNOW they don't have any stds. I know it sucks, but really, do you want syphilis in your mouth? Keep it clean and careful and you can still have fun.