Is it normal?

Yesterday I went to work (housekeeping) came home & took a nap & when I woke up my heart was beating fast & I felt out of breath. A while after I still felt like I couldn’t catch my breath although I was just laying down. Today I woke up feeling fine & at work again I felt bad & been feeling like I can’t breath normal since, but I’m not gasping for air either. Is this normal? Could it possibly be dehydration? I’m not the best at drinking water tbh ;/ yesterday at my 20 week appointment I let my doctor know that I run out of breath quick & she told me it could be caused by a hormone but to be sure she made me an appointment with a cardiologist. I’m just scared that something can happen to me or to my baby, I had my anatomy scan & everything came back normal it’s just that I’m a first time mom so I freak out about anything lol