worried !!!

Hi this is completely random but Ive been worried.. So like a few weeks ago when March first started I was smoking weed  and I took a gigantic hit and got so high I thought I was dying. I have never felt this before and I got so worried but calmed down and went home. For a whole week after that I thought I was dying  and I finally relaxed, I was so stressed my period was late by 5 days. Anyways I calmed down then smoked again once April started. I had another panic attack and I thought I was dying AGAIN. It was terrible.. So I went home and relaxed and felt better the next day. I decided to try smoking again, 3 days later. I had another panic attack and my heart was beating fast and I realized I started to see black dots. I figured it was just because I was high but then 2 hours after the black dots did not go away and I started to realize I am having a problem taking deep breaths, it feels as if I'm not getting enough air into my lungs but sometimes i can get relieve. It's been 3 days NOW. I have no serious problems besides this and back pain and I honestly have been so stressed. WHATS HAPPENING. is this anxiety?? Would it have lasted this long? NEED FEEDBACK.