I got into bed tonight and was laying on my stomach and I started to get a sharp pain in my central lower abdomen, I sat up and felt nauseous and had very short breaths and felt like I had forgotten to breathe properly. My hands became a little shaky and body tense and a little twitchy. Also, I'm so bloated it looks like I'm pregnant, my stomach is hard and big when I stand up. I haven't been for a "number 2" since last night and I'm currently on my period. What could this be and/or what is causing this!

Depending on where the pain is your apendix could be the culprit. If the pain persists I'd see the doctor as soon as you can. Or you could have a bowel obstruction.

It starts about an inch above my belly button and a finishes 2/3 inches below my belly button. Its been going on for about a week or so but not this bad at all. Very difficult to pass excriment but I have been burping a lot! I have just moved out into my own flat and I'm not registered at a doctors at the moment, would a nhs walk in centre be able to help?

My mother was a nurse and she taught me that your appendix is situated right above the right hip bone about 2 fingers next to each other.

What concerns me is the burping and nausea. You could have some gallbladder problem also. If you have sharp pains in your back right under your shoulder blades then it's the gallbladder.

I am in the US and don't know anything about England's NHS, but I'd call them up and do whatever you have to do to get into the doctor's before you have to be admitted into the Emergency Room.

Periods, constipation, and gas all produce those symptoms.
You've said before that you tend to be constipated. Work on that.
But I also agree with twink. Appendicitis doesn't have to be acute; it can happen slowly. Gallbladder problems do cause gas, nausea, and bloating.
It's impossible to diagnose online.
But given the questions you have asked here before, I wonder if it's just nerves and constipation.

If your pregnant 3 month and you have stomach pains and bloating and is hard for you to breath