What causes chronic fatigue, nausea, loss of appetite, dizziness, blurred vision and overall achiness. Blood tests. Low vit d/b12, high calcium/pth?

Those things can,,, All the things you mentioned can give you many of those symptoms. Vit B12 deficiency especially can do it. The high PTH is a concern also as it can mean a possible adenoma, so it would be smart to see your doctor for therapy to correct your deficiencies and find out why the ca/pth is high. Best of luck.
High calcium. High calcium from hyperparathyroidism is associated with many non specific somatic symptoms that overlap with other diseases. Chronic fatigue, brain fog, aches and pains, and reflux are just some of the symptoms which can improve or disappear with parathyroidectomy.