I'm on my period and I keep having this weird vibrating sensation in my lower abdomen, what could it be? Feels like a vibrating cell phone.

Unclear. Can you feel it with your hand--is it like a spasm in your abdominals? You might also try Motrin and a heating pad. Sometimes our nervous system can interpret one type of sensation (such as an ache or cramp) as a different type of sensation. I would advise an evaluation at your doctor.