Im 21 ans recently sex has been very painful also i haven't been getting wet, i was tested for stds and infections but nothing came up what could it?

Need to examine : My advice increase the length of foreplay, use lubricants. If it is your first time than it could be change in bacterial flora, due to excessive cleaning, wiping, etc, do not over clean the area. Sometimes just the initial sexual activity itself can cause change in vaginal flora leading to infections. There could be other reasons see a doctor if above measures fail.