After sex my vagina was extremely swollen and still is somewhat today. also a couple hours after sex a watery clear substance leaked onto my pants why?

Couple of issues: This could be an infection like trichomoniasis or something else. If you are using a condom or a lube, it could be an allergic reaction. I would see your ob/gyn to rule out infection first then it may be necessary to have a gyn visit the morning of or morning after sex, so your gyn can evaluate what is swelling. Could be a bartholins or skenes gland cyst as well.