I Am 22 Weeks Pregnant And I Have Been Having

I am 22 weeks pregnant and I have been having weird, irregular heart beats tonight. I got up from laying down and it felt like my heart stopped a couple of times, after that it was a slow, weak heart beat. About 15 minutes past and then my heart started beating really really fast, I thought I was about to have a heart attack. I feel tired, headache, & kind of nausea. I'm worried about my baby. Is this normal? Or should I go to the emergency room ?