Nipples hurting?

I haven't had a period for 6 weeks (all pregnancy tests negative) I was on the pill and due to being busy and doing a lot of travels I haven't taken them in about 3 weeks. I was trying to wait until my period came to start a new pack and get back on track. A few days ago I noticed my nipples so sensitive when touched, it's very painful. I was taking my pill regularly the last time my husband and I had sex. He has been out of town due to work for almost a month now. I'm just trying to see if anyone has any advice or suggestions as to why I haven't gotten my period and my nips feel like they are dying. Thanks in advance!