Do they last this long? Am I just going crazy?

I feel like I should be running, there's so much nervous energy, and there's a pit in my stomach and breathing feels weird and difficult. 

I just can't relax, nothing is helping me relax. 

I'm not even entirely sure why I would be anxious (other than general anxiety disorder, but I'm medicated for that). I have a few ideas but not a specific concrete intrusive thought.