Hi,
Are there associated symptoms like weight loss or change in apetite or bowel movments?
Considering your symptoms I think the pain is due to Cholecystitis(inflammation of gall bladder) which can be due to a stone in it.Though nausea is also present in this case but it is not always observed in many patients.Abdominal ultrasound will be diagnostic towards it.
Other possibilty is that pain can be cardiac in origin if you are having breathlessness or fast heart beat or any other weired finding.However as you have not mentioned any of these things so I beleive you should consider inflammation of gall bladder.
Regards,
Dr.Naeem
Doctor (MD)
Medical Doctor,Ireland.