You also mention that you have a history of depression and that you are taking medication for this problem. Several of the symptoms that you list - such as depressed mood, social withdrawal, sleep changes, and appetite and weight changes - can be the result of clinical depression. After seeing your primary care physician, it may be useful to consult with a psychiatrist - in order to clarify your current psychiatric diagnosis, and also to evaluate whether your current medication regimen is appropriate for your condition. In addition, there may be useful non-pharmacologic strategies for treating your depression, such as cognitive behavioral therapy or other psychotherapeutic approaches.
Finally, you mention that you have a high-pressure job and that you have been putting yourself under a great deal of stress. It is worth remembering that stress may exacerbate a broad range of psychiatric and non-psychiatric medical conditions. In addition to seeking medical help, it would likely benefit you to find ways to reduce your stress level - through leisure activities, through exercise, or simply by reducing your time spent on work.