If i take a multi vitamin should i continue my 3000 mg of vitamin d as well as iron?

Depends: what is in the multi vitamin there probably already has the iron and some vitamin D Take those numbers into account when determining how much more to take

Yes: If you are taking the vitamin D because of deficiency it is a small dose. The way we make vitamin D in the body is by skin exposure to the sun. Taking it by mouth is a poor way of getting vitamin D because it is absorbed poorly.

Vit D level: It would be helpful to know your vit D level before advising you on the proper dose of vit D would be for you. If your level is normal, 400 to 800 units daily should suffice. Since you're a menstruating female a daily dose of iron can be helpful but the amount in a multivitamin is usually small. Therefore if your periods are very heavy, you would need additional iron supplement per your MD.

You may need to: As the amount of iron and vitamin D may not be optimally dosed for you based on any underlying deficiency or co-existing medication condition you have. It isn't uncommon for people to have to supplement a multivitamin when they have coexisting vitamin deficiencies.