I am 21 never been on the pill. But for the last 2 months I have been bleeding for 3 weeks the first 2 weeks are not heavy but not light eather. And now I'm having back pain and stomach pain but not like cramps and my nipples anr very itchy am I OK

Any usual bleeding should be checked by your doctor. It could be something relatively common and simple to take care of, it could be something they would want to look into more.