My gums aren't bleeding. They're just sore on the upper gums on each side, like above only two teeth on each side....not all of my gums are sore. I'm pretty sure, in my case, my body is detoxifying (as smitti1 pointed out), and the pain should gradually go away within a few more days. I've read it takes a week or so for the detoxification process to be completed (as far as sore gums go).
At first, I thought it was from vaping caramel and fruit liquids, but after I remembered this recovery symptom of quitting smoking, I felt a little relieved. If the pain continues, I'll have to come up with plan B.