please help I'm finding it very hard to breath due to severe anxiety
I'm on the same level as you. Try yoga, it's helped me massively, or any excercise, I know it sounds crazy but it helps. All about calming yourself down, trust me a few days ago I was suicidal so I know How you feel. Stay positive and know you can and will get better.
Breathe in through your nose only for a count of 4 seconds hold your breath for 4 seconds breathe out slowly like you're trying to make a candle flame flicker in front of you for 7-10 seconds. Hold your breath forn2-4 seconds then repeat the process up to 5-10 times. Never gasp for breath through your mouth. Don't sigh. don't yawn. Breathe only through your nose. Let me know how you get on.
That's a horrible feeling, what helped me in the past was: sitting comfortably somewhere, breathing in through my nose and out as slowly as possible through my mouth, making a soft 'pfffft' sound. At first it can feel a bit uncomfortable, but if you keep doing it for a while, you can feel more space freeing up in your chest. It probably has about the same effect as the exercise rawb mentioned.
Do it three times a day, you'll soon find relief.
I learned this from a yoga teacher, you might consider trying yoga, like jack85856 already suggested.
Doing breathing exercises maybe won't solve the cause of your anxiety, but it can help tremendously in breaking the vicious circle; bad breathing technique can cause anxiety all by itself!