Hello,
So there is absolutely nothing in your description of your sexual activities with this person that concerns me at all. Herpes looks nothing like a hemorrhoid so I think you’re safe there.
The buttocks skin does NOT shed. While genital skin is thin and virus can be shed easily, the buttocks skin has a thick layer and thus shedding cannot occur when there is no outbreak present. I think your scrotum touching her buttocks is completely risk free.
Also, putting your finger in her vagina very briefly, then wiping it on a linen before beginning to masturbate does NOT present a risk to you. One of the things about transmission is that there has to be sufficient volume of virus present for infection to occur. I definitely don’t think this is the case for your contact. And I don’t think the back pain has anything to do with your contact, unless you moved your body in a way you normally don’t move it and it just kind kind of out of wack with a strained muscle.
It sounds like you were very carefully to practice safer sex in this situation.
Terri