I'm currently taking a multivitamin, fish oil and 4000iu of vitamin d. is this to much vitamin d? can this be harmful?

Probably safe: During winter, most people are even more deficient in vitamin d than when they have exposure to sunshine. 4000 iu of vitamin d is safe, and this amount is often indicated especially in winter months. You can ask your physician to test your 25-hydroxy vitamin d level to see where you are in replacement, and adjust your dose accordingly.