Vit d is 17, what else do I need?

[confusednorthner]

Gp has rung and confirmed my vit d is low at 17.3 and has put me on 20'000iu a day for two weeks then over counter dose. What else should I add to help please? I've read magnesium and K2? No idea what K2 is and how much?
Any advice gratefully received as I'm feeling old and knackered!

When mine was tested at 12, the consultant told my GP 20,000iu a day for a fortnight then 20,000 once a week. When it was retested recently it was just above the lower limit of normal, so I was told to carry on with the 20,000 once a week. GP also said to get at least 20 mins of sun per day from I think April to Sept with bare arms. I think she also said to take it with food to help it be absorbed.

The best thing is sun. Including normal day light. Try and get outside as much as possible