You have been told this is not a risk. The ways that HIV is transmitted has been told to you and this is not one of the ways. And yet you still worry. Could the problem really be anxiety? I think so. If you treat anxiety like the disorder it is and treat that, your HIV fear may go away. You had no risk and any type of 'symptom' you think you are having is not associated with your visit to the spa.
Even if she was HIV positive, there is no way, as in ZEEO chance that you would be infected by what you described. HIV can only be transmitted inside the body through unprotected anal or vaginal sex. You need to stop worrying because you're as safe as anyone else who never had any risk.