I have had upper stomach pain for a month now/ no appetite and weight loss, now i have extreme pelvic pain with dhiarriah what could this be?

Get evaluated please: It's normal to be concerned about your health, and to worry why you feel bad. The possibilities are numerous--ranging from GI to non-gi causes, ; even stress. Alarm signs include weight loss, bleeding, recurrent vomiting, significant tenderness. Whatever the reasons, you're appropriately anxious about it ; should seek medical help asap, particularly if your symptoms are as "extreme" as you report.