How do I know if my abdominal pain is serious or not?

This morning I woke up and laid still for a while, and then turned over and stretched and immediately thought I had pulled a muscle or something. I got up and went to the bathroom, and whenever I flexed or moved my stomach, there was intense pain. It got worse, and I laid down and for a while it hurt even when I was laying still. The pain was mostly on my lower right side and was more wide spread. Now it's more in the middle in a concentrated spot, but my right side still is achy. It was sort of radiating from my belly button earlier but now it's just in that one spot right in my pelvic area. If I press down on my right side where my appendix would be and let up it doesn't hurt, but if I press in the middle in that spot where the pain is mostly now, there is considerable pain. I think it could possibly be appendicitis, and I have heard of people's appendix bursting and it wasn't unbearable pain and they thought they had just pulled a muscle. But I'm thinking that it might just be gas, because I love refried beans : ) and have eaten them for lunch the past two days. I have had severe pain in my chest before and thought I was having a heart attack or something, but it always was just really bad gas. I am already over my period and everything so it can't be that. So I don't know if I'm just being paranoid or what. I guess I'll just wait for a couple of hours and see if the pain gets worse, but until then, any words of wisdom?