I am 10 days late for my period I am not pregnant. I have been on antibiotics for sinus infection for three weeks but been on them before and it's never affected period I am normally to the day. Regular. I have had all the symptoms of my period cramps head aches lower back pain but no bleed any one give advise?

Being to the "day" is more the exception than the rule, unless you are on birth control that regulates it.

I assume you are not having sex, since that is the only way you can be sure you are not pregnant, or medically just can't have kids.

But it can be a reaction to the medication this time, that happens, it can be another issue as an infection, or just your body adjusting and having a hormone change or imbalance at the moment.

Really nothing to do, but wait for next month and see if it comes back correctly, It is not all that uncommon for some women just to miss one every now and then.

Also not knowing age and even weight can have issues with this.

I agree with Chuck. Are you not having sex, and that's why you know you're not pregnant? If you have had sex than pregnancy is a possibility.