What Causes Elevation In The Heart Rate After Withdrawal Of Contraceptives?

Hello, I recently stopped birth control (close to two months) and have noticed around ovulation that my resting heart rate skyrockets, last month I had to go to the ER twice for 165 resting heart rate and again today it happened. I am ovulating this week according to my period tracker. I have been prescribed beta blockers as my cardiologist can t seem to figure out where the high heart rate and blood pressure are coming from. I want to know if this is due to coming off birth control and if so, how long will it take to get better. I am scared and blood tests have all come back normal, including thyroid test. Is there any supplement I can take such as Vitex? Or would that make things worse. I am healthy, 31 years old and just got married. There are periods of time where I feel fine (beginning of period for the first two weeks), I am open to natural herbs/supplements.