Yes, you should recheck your vitamin D levels regularly. It is suggested to do this every 6 months. Your doctor should have prescribed a weekly megadose. If you're taking this, you still need to take at least 2,000 iu vitamin D3 everyday. That's how both my conventional and natural doctors had me do it. I still take 5,000 to 6,000 iu vitamin D3. I buy my vitamin D3 from swansonvitamins.com. Like you, I was dangerously low on my vitamin D before doing this.
I have been suffering with all of your symptoms for years and finally a few months ago after being tested for anything and everything was diagnosed with a vitamin D deficiency. I have come to realize that this is so common but for some reason is left undiagnosed in most people so consider yourself lucky. I started taking Spring Valley brand from Wal-mart and was seeing improvement in my symptoms but then I switched to more expensive brands from the health food store and progress came to a stand still. so today I went out and bought the Spring Valley D3 5000iu and almost immediately I could feel an improvement. It was like something was lifted and I just felt happy. If you read other posts, there have been other people that experience the exact same thing. Once you start taking the D you should start to have good days and bad days and you will know that it's from the D. I've read articles that say it can take up to nine months for full relief. If you take 5000iu a day your levels should be in the optimal range in two months. The 50,000iu D2 prescription that the doctors give out is not reccommended.