Suggest Treatment For Clinical Depression, Loss Of Appetite And Sleeplessness

I have a 17 yr old female employee that has been diagnosed with clinical depression, she is currently taking an off brand of Zoloft, 25 mg. I have noticed lately that she is very moody, like one minute very happy the next very angry or just flat out in tears, she has a loss of appetite and she is not sleeping well at all. My concern with this situation is the fact that she drinks 4 to 6, 20 oz redbulls on a daily basis, now I know that these energy drinks are fine in moderation but she is way out of control with them and Im concerned that they may be affecting her medication as well. What can I do to help her or what kind of advice can I give her since she trusts in me and talks to me when she really needs a friend.