Help...erotic reading

So recently I have read this fan fiction which I can call an erotic fanfic and I felt somethings stinging and a weird feeling in my stomach and I released something which is called I guess cum I'm not sure but idk what to do ( btw I'm on my period ) is it normal for this to happen just by reading and erotic fanfic and its been few time that I read and erotic fanfic ( I'm not in my period most of the time tho) and I guess I cummed , I'm not sure what it is but when I searched it up that's what it came up , it said that its called cum . But it's my first time and I'm really confused so I don't know what to do plz help ㅜ_ㅜ and tell me if its heathy or no or is it normal or not .....( I'm 13 btw :/).....