As a Hepatitis B carrier you should really not encounter any symptoms from this. If your doctor in the UK says that your liver and kidney tests are fine - then you need not worry about serious kidney disease. It is difficult to say what the pain in the back between the ribs is. Kidney stone pain is lower and is so severe that you would not be able to do anything - this does NOT sound like it. If you do not have urinary symptoms e.g. burning pain on passing water, passing water frequently and passing smelly, cloudy urine - then it cannot be a urinary infection. If the pain is higher up in the back of the chest - then a chest X-ray might help - particularly if you have been travelling a lot and been sedentary. A bloating stomach is probably related to anxiety but I do not have all your details to say much more. Hope this helps - does not sound serious.