I think my anxiety came back...plz help:(

Hello Guys im new to this site and i just wanted opinions from you guys. So on September 11 of last month i suffered on what i thought was a heart attack or stroke, im 21 now but was 20 at the time. I was told it was a panic attack. Days before i had headaches but im pretty sure it was form the lack of sleep and going to school early in the morning. For about 3 weeks after the ER visit i had headaches and the usual anxiety symptoms, went my GP for a follow up of my ER visit, he said my headaches were from worrying, stress, etc. He prescribed me with 50mg of Hydroclorothiazide and 50mg of Serthraline. Took it for 2 weeks felt better no Headaches for awhile feltgreat, even went to my cousins football games for the first time...i was affraid to leave my house. Then this day came(10/11/10) i was in Vegas for the weekend i had a headache, right away i thought oh no:(. I was thinking to myself well i havent been sleeping my usual sleep pattern(been going to bed at 4:30am 7:00am, etc) when i was their. That night i had a monster energy been trying to quit caffiene for weeks now. So now i have a headache even after getting home and now im worried again and told myself well my anxietys back cuase im thinking the worst, and always look up the symptoms online and getting scared of what can be the cuases of headaches and im thinking im going to die soon:(. I have no health insurance since im now 21 and no longer on my moms health insurance, The doctor even denied my request for a head scan that day cuase he dosent think i need one ...any advice is apprieciated