Hello,
There are numerous reasons why you could be experiencing this. One would be Pelvic Inflammatory disease (PID). I would certainly see a gyn and ask for some tests and also an early pregnancy test as well.
Well, I am no doctor, but I would say even a doctor would have a hard time giving you an answer. I am not familiar with the term "toilet disease" so I am not sure if that could cause the discharge. I do know pregnancy often causes some very brief spotting going by my own experience, Whether the sex was short, as you indicated, or long, would make no difference as far as getting pregnant is concerned, either would pulling out "in time" as long before that there are pesky little sperm swimming about. There may be millions and millions of them but for pregnancy you only need one.
Anyway, you'll have your answer soon enough, and if you aren't pregnant I wouldn't worry about a little spotting, unless it keeps happening.
Freefalling