Do i need to seek immediate care if i'm bleeding for more than 3 weeks?

How much??? If you mean vaginal bleeding it would depend on the amount. If you fill pads daily you should go in immediately. If there is a trickle daily you can schedule a visit when convenient. When you post on this site the more detail you provide about an issue the more focused we can make the response.

Bleeding from where? Either way this is not normal. A physician visit is a good idea. If you are dizzy, lightheaded, or if the bleeding ks very heavy, then please get seen today.