Pregnancy or period symptoms ?

I'm due for my period in 5 days says glow which is usually regular. But the last two days my back has been sore, small cramping, and headaches. I have also had slight acid reflex the last week which is really usual. I've also been under a lot of stress. I'm 27 and have two kids but it's been so long since I was Prego I don't remember my first mth. Any comments??