Husband is fixed, but my period is 4 days late and have had a lot of menstrual cramping. should i be worried about being pregnant?

Vasectomy: If your spouse performed his post vasectomy semen analysis and his count was negative you should be fine and you're likely having menstrual cramps. You may not have ovulated and the delay makes the cramps worse. However, if he just assumed the vasectomy worked its never a bad idea to do a pregnancy test. 1% or less of vasectomies fail.

Pregnancy: After a vasectomy, the partner is usually tested to determine if sperm is still being made. See if your husband had these followup tests. There is a small chance that he could still be fertile, but less likely if the tests showed no evidence of sperm. You may have cramps just because your period is late. I would do a pregnancy test if you do not get your period within 7-10 days.