How to convince parents to let me stay home sick?

I had this 2 weeks ago, it's terrible. It's a cold, basically my sinuses are really clogged and I cough a little although it does hurt. My throat is REALLY sore. But, I did miss monday this week already because I went to my cousin's wedding so my mother might not want me to miss today. I don't want to fake anything because it's really untruthful. I just want to stay home sick, I don't mind doing my homework or reading I just can't go to school like this!! What could I say to convince my mom to let me miss today? I've already missed a day this week and she is not very wild for the whole "stay home sick" because she ALWAYS ALWAYS thinks i'm faking.