There can be various reasons for the pain in right side of abdomen under your rib cage like
Gall bladder stones,cholecystitis
,kidney stones,Duodenal ulcer
Since you are having loss of appetite,upset stomach along with radiation of pain to your shoulder blades,it suggests a possible gall bladder infection
You will have to consult your doctor and get proper investigations including ultrasound
abdomen done for the diagnosis.