Hi there owlbab, and welcome to Scarleteen!
I can't say for sure what's going on, because I'm not a doctor, but in all likelihood what you're experiencing is normal. Did your boyfriend wash his hands beforehand, or use a glove? If not, that could be an explanation - introducing something else into the vaginal environment, whether it's unwashed hands, someone else's saliva, or sexual fluids, can mess up the pH balance and change the discharge that you're having.
It could also just be normal variation in discharge that happens sometimes when we're in different phases of the menstrual cycle, stress, changing diet or hygiene habits, etc. You can read more about what's "normal" for discharge over at Honorably Discharged: A Guide to Vaginal Secretions
In all likelihood, this is nothing big to worry about and will resolve within a day or two. You're doing the right thing in terms of keeping an eye out for things like itchiness, pain, or discomfort, because those are clear signs that something's up. If it gets a lot worse, or those symptoms come up, you should definitely check in with a healthcare provider. But like I said, in all likelihood a little bit of time, rest, and self-care will get things back to normal!
I did want to take a second to address what you said about bleeding and/or soreness. Is that a regular occurrence for you, during fingering or any other sexual activities?
If you're experiencing bleeding or soreness afterwards, it's a good indicator that your vaginal tissue was injured as a result of not using enough lube or things being a bit too rough. It could also be a result of the other partner's fingernails being trimmed and filed (ouch!). It's important to listen to those signals your body is sharing, not just because you're being hurt, but also because it can increase your risk of STI transmission and bacterial infections. Does that make sense?