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The description is highly suggestive of Sick Sinus Syndrome
or Postural hypotension
You may have to repeat the monitoring of the rhythm - for 24 to 48 hours.
You may have to do 24-hour monitoring of blood pressure also.
Do not jump out of the bed - sit in bed a few seconds / stand by the bed a few seconds / then start to walk. To look at the sides - turn the whole body and not the neck alone! / and that slowly...
Wishing speedy recovery