What could be the reason for increased yellow discharge and irritation in the vagina after having unprotected sex for the first time?

Hi doctor,

I had sex for the first time a few years back. I am 18 years old. My partner's penis is quite big, and it did hurt a lot. He wasn't exactly going slow the whole time, either. It was unprotected sex, also. That same night I began to realize I was producing abnormal amounts of discharge once I woke up. I ignored it for a few days, but then I realized after a few days that there was a lot being produced to the point that my underwear was getting damp from it. I sleep naked, so when I wake up and it'll be very damp down there, and I physically feel it dripping down my leg. The discharge is very runny, odorless, and yellow, but there is so much of it that I have been wearing period pads in my underwear to stop it from leaking, and I've had to wear underwear to bed. When changing the pad, there will be a lot in the pad. My vagina was swollen and tender, not itchy or burning. However, for about three days urinating was uncomfortable only because it felt as if there was a cut and was irritating it. So I decided to investigate and look in my vagina in the spot where it hurts, and it looks as if there's a cut or something in the opening of my vagina. The cut is a few mm, and the surface of it is white, and around it is red. It looks like an internal cut. It hurts to sit down, so I have to slowly sit down, and I cannot walk comfortably because I am constantly feeling it rubbing against the other lip. It hurts when walking, sitting down, and moving in bed are very painful. I have no idea what it could be, but it hurts a lot, and it does feel like a cut, but then why is there increased amounts of odorless yellow discharge? Kindly help.