What Causes Fatigue Along With Stomach Ache?

Not feeling quite right. I have dropped 20 pounds since January. I have not changed my eating habits or trying to lose weight. I have several new bruises almost daily. I feel exhausted most of the time and today a new symptom of stomache ache, not really a cramp but just feels tight (lower abdomen area). I do suffer from Celiac and anxiety disorder. I am currently taking Prozac 40mg/daily and Vyvanse. Any suggestions?