Was this a panic attack?

Just for info, I'm a 21M. While I don't believe I've had panic attacks, I've experienced pure-OCD throughout my life. Lately, I've been obsessing about my heart, this obbsesion was triggered because someone I know (32M) died from sudden heart failure in addition to that I have had some minor problems with my heart and believe that I’m having some symptoms ( or it may be my OCD). So I've made an appointment with a cardiologist this month (still 3 weeks to wait). In the last two weeks, I've been constantly checking my heart rate, worrying, and obsessively googling all symptoms. Today, while I was the bus with a friend, I started experiencing shortness of breath, shortly I got dizzy and confused then I started feeling anxiety and those symptoms were getting worse and worse, I was barely able to speak and think in addition I was shaking, I felt like I was going to die now . After sitting in a nearby cafe for about 20 minutes, the symptoms gradually subsided. I'm now at home feeling a bit confused and anxious. Could this be a panic attack, or might it be related to my heart problems? Thank you in advance.