Sending nudes but on my period

I’m usually a shy person. You’re probably gonna say I’m not shy since I’m doing sending nudes but I still am. Anyway the guy I’m talking to asked me to send nudes but I just got my period today. How can I calmly say I’m on period and if I can send it next week? I kinda of don’t want to just say straight up “I’m on my period” something more like “do you mind waiting a week?” He’ll probably ask why after which I’ll have to say I have my period but I kinda feel so weird saying it. Is there anyway I can calmly say it to him?