As far as I know it doesn't matter where you test but the side of the finger end seems to be the normal place. If I get a reading that seems out of place I always wash my hands well again then test on the other hand.
It is possible you have a bad batch of testing strips, as previously suggested, if you have a control solution check with that, otherwise try a different pot of test strips, try and make sure that the batch number is different. If everything still give high readings you might want to try at a chemist as many of those do blood glucose tests, or book an appointment at your doctors for a blood test.
Are the 13 - 15 readings all the time or just post meal or morning fasting, what are you eating and how much is that putting the readings up? What type of levels were you getting before? What medication are you on? If you give us a bit more information about what your readings are like through out the day and what you are eating, then we might be able to give you some more advise.
Finally try not to panic too much, being stressed out will put your blood sugars up as well.