Hey, Doodle. =]
I've done a lot of the things you have, sweetie! Calm yourself down, first of all, close your eyes, and find your voice. The best thing that I do is I whisper my name out loud, and then say it out loud in my head. That way, you find your voice and your center. Repeat it a few times, and tell every other voice to quiet down, alright?
Next, with the feelings... Take a shower, wash yourself and relax! Then, put on your most comfortable thing to wear, find the thing that comforts you most, and relax.
Drinking herbal tea is good for feeling centered.
You should learn all about energy, and you should learn one kind of shielding. The one I learned is called White Light Shielding. Know that kind of shielding, get it to where you can use it in an emergency, so you can go through all the steps easily if you feel overwhelmed like you did earlier.
If you have anything else to say, PM me sweetie.