Hi it feels like i'm not breathing deep enough, which results in me yawning all the time. some days getting needles and pins in my face? i'm worried? it also sometimes feels as if there's a knot in my chest? what could this be?

Anxiety: If you're not experiencing true shortness of breath with exertion and your symptoms are noticeable at rest, anxiety is the likely cause. Pins and needles sensations are commonly caused by hyperventilating, also seen with anxiety. Your chest tightness is also characteristic of tension and anxiety. Speak to your physician about getting stress management therapy which I feel will help you a lot.