Hi there. It could be what Anniebrooke says. But there are other things too. It doesn't sound like anything sexually related, you'd not get an std from a toy that belongs to you and you haven't had sex for a long time. I would not think this is herpes if you've never had an outbreak before and haven't had sex in 6 months. So, what other things could it be? What about inflamed or infected hair follicles? https://www.mayoclinic.org/diseases-conditions/folliculitis/symptoms-causes/syc-20361634 That can look like a pimple. Cysts and boils are very common as well. https://www.healthline.com/health/womens-health/vaginal-boils Keep your hands off of it though. Your hands have bacteria on it that can transfer to it and cause infection. You don't want that. Is it painful by the way?
I would guess that it's nothing, maybe a blister from your prolonged use of your toy. I don't think herpes lesions look like normal skin with a little blister full of clear water, and I don't think they happen out of the blue after a number of months. (You might post this in the Herpes community just to check, though. They're the experts.)