Vitamin D2 causes the amyloid protein in your brain to clump together making it difficult to remove this build up of amyloid. This leads to loss of cognitive function and sets up the conditions for Alzheimer's disease progression. Vitamin D3 helps clear amyloid from the brain which aids in improving cognitive function. Keeping 25(OH)D3 levels at or above 50ng/ml [US] or 125nmol/l [UK] is an important factor in reversing cognitive decline. And if that isn't bad enough we have also known for years that Vitamin D2 speeds up the rate at which your body disposes of Vitamin D so the more D2 you take the more you require. Vitamin D2 is also less effective than D3 so you need more D2 to get the same effect as D3. Recent research on professional athletes shows that supplementing with vitamin D2 does increase muscle soreness and recovery time after bouts of intense exercise.
d2 is the wrong one to be taking d3 is the one you want to take.you get d2 from vegetables and fruits.your d3 went down because it was going down and will continue to go down are you taking d3? try getting sunlight on a daily basis go for a walk or a hike.exercise is helpful .do you have any symptoms or some type of infection or autoimmune disease?bacterial infections or fungal infections can cause this condition. like yeast among others.hope this helps.