What Causes Sudden Panic Attack After Drinking?

I drank in the afternoon, slept for 4-5 hours woke up feeling fine and sober, I went to the grocery store and while there had a massive panic attack and had to leave, i had problems finding my vehicle and was pulled over a couple of blocks from the store, someone had called in about me wandering the parking lot. I went to the doctor and was diagnosed with Grave's Disease, t4 was high 1.92 and t3 was 9 something tsh was below .0025. I was arrested and by the time they got me to jail and drew my blood i felt fine again although very tired from the stress. My blood alcohol came back >= .15 which seems impossible given the amount i drank(200 ml) and the time involved (11 hours)