I was invited to a particularly stressful family get together last Saturday (19th). I had an awful night that I began having my first panic attack, but- it hasn't stopped? I've been in a panic attack state, Heart palpitations, sweating, shaking, hard time breathing, vomitting/diarrhea, hot and cold flashes, thankfully I sleep fine (minus the hot flashes). 
I went to the hospital a few days after because I realised this wasn't a hangover (I had been drinking that night). They did blood work, urine tests, and a heartgraph, but they said nothing was wrong and it must be anxiety. I was given 5 days worth of 0.50 xanax to tide me over.
It makes me quite drowsy, so I only take 0.25 once in the morning and I'm trying to handle the attack without any xanax at night (because I'm nervous of growing a dependence on it. (Is that a silly thing to worry about?))
I was very scared up until yesterday, but I know this is not dangerous, no matter how terrifying it may be, and that this shall pass. 

I am just curious if anyone else has had an episode that lasts this long? Or what kind of therapies or exercises work to control physical symptoms better?