I used to have panic attacks, I never saw a doctor because it was all in my head...and they finally went away.?

But... during the night I wake up hyperventilating...and its really insane because this is by far worse then any panic attack I ever had...I can't catch my breath my heart rate/ beats not normal...It seriously feels like I'm having a heart attack.. It takes me a while to calm down...because I'm so disoriented during the night of course, sometimes I'm scared to fall back asleep thinking that I won't wake up...its crazy..and its not like during this or before this happens I'm having a nightmare. It even happens through the first 15-20 min. I have fallen asleep...( I clocked myself) ...anyway can anyone give me advice or any information..maybe its some kind of sleeping disorder but I doubt it cuz I sleep good..excluding the.."panic attacks" so Ye any sites, or information would be helpful..should I go see a doctor? Is this really serious? What's it caused by? Should I go see some specialist? Lol serious though..no rude or stupid comments please...Thanks