I have been on Welbutrin XL 300mg for 3 days now. I switched fro...

I have been on Welbutrin XL 300mg for 3 days now. I switched from Lexapro, which I was on for 2 years, because of weight gain...over 30 lbs in the last 2 years. I am a very active person and have a very active job. This prompted me to talk with the doctor about my weight gain. He recommended the Welbutrin XL, which I take one pill at night before I go to bed. I have been VERY edgy ever since I started it. I dont know if it is withdrawl from Lexapro or switching to Welb. I have also had the common headache all day every day since I started...if anyone has any clues, please post! Thanks