I know I have a yi from taking antibiotics, but when I feel inside it's moist and swollen & sometime hurts. I have no std's, so is this just from yi?

Most likely. Since antibiotics kill both undesirable and good bacteria, they change and alter the balance of the normal flora of the vagina allowing for an overgrowth of yeast (candida) in the vagina and development of vaginitis. Symptoms include vaginal whitish discharge, itching/burning, redness, and swelling. Rx with otc and/or prescription antifungal vaginal creams, tablets, suppositories, or oral med.