When Should I See Improvements?

Hello,

I received my labs, indicating a severe vitamin D deficiency (7 ng/ml). Took the 50,000 dose vitamin last Thursday, and now this week’s Thursday. After taking the vitamin, in the following days, I do notice an increase of lightheadedness and dizziness. Was told by my doctor to take the vitamin for 8 weeks and then a retest for regular maintenance dose. After two weeks though, I haven’t been feeling better with the feeling derealization, dizziness, light sensitivity, etc. When should I start to see feeling better?