Hey Machelle,
The feeling that you can't get a deep breathe is definitely anxiety... that's how it started for me. You in turn continue to try and take a deep breathe which has you getting too much oxygen and essentially hyperventilating. These actions are not purposeful I'm sure but are an effect of being nervous and anxious, as is your "brain fog" you are probably hyper aware of how you feel every moment because you are worrying and this can lead to the inability to concentrate on much else. When this happens your focus is centered internally making everything feel fuzzy or foggy when you attempt to change your focus to something else. Hopefully this makes sense to you. I have felt everything that you describe.
The "twitching" can happen if you are very tense (even without realizing it) your muscles are experiencing the "stress" reaction brought on by anxiety as well. I'm not certain if you are taking any meds, but the side effects are often tremor or "twitching". Go easy on yourself and try to stop worrying - it's likely the worrying is causing everything else. Go to your Doc. if you're worried they can ease your mind. Good Luck!!!
Liz