Upper back pain present for almost a year now. pain started after dieting and losing weight.it is not present with rest. it hurts w/ activity /sitting?

May not be related: Congratulations on your weight loss. But, do not blame a purposeful weight loss with back pain. In general, weight loss is good for the spine. But, in the effort to increase metabolism, sometimes we over do it, or, by age 40, having back pain is common. For most people, rest does relieve back pain. Pain with sitting usually indicates a disk issue, which is unfortunately very common.