I got my period on March 16th and had sex unprotected sex on March 20th which was the last day of my period. He pulled out before he came in me but I'm scared of pre- since we had unprotected sex again later that night and he didn't go to the bathroom. I've been eating a lot lately and I have been really tired but I also was prescribed benadryl by my doctor because of an allergic reaction I had so I was thinking the medicine makes me tired. I've had some small cramping and a really light brown discharge color after I go to the bathroom and wipe. Am I pregnant or am I just imagining things?

Any time there is intercourse, especially unprotected, there is a chance for pregnancy. That being said, there is no way you would be having pregnancy symptoms at 9 days after you became pregnant - if you became pregnant. I would suggest waiting until your next period is due. If you miss it by a week, take a pregnancy test. There is no way to know whether you are or not pregnant at this point. Chances are your own body isn't even aware if it is pregnant. In the meantime, use protection from now on if pregnancy is not what you are wanting. Good luck.

In addition to what alkalineangel said, the slight cramping and discharge may have been due to ovulation. Some women will experience this once in awhile when they ovulate. See what happens when your next period would be due.
Being very tired while using Benadryl is common. The ingredient is sometimes seen in medications used to help with insomnia.