What Are Effects Of Stopping The Intake Of Atenolol?

I am a 45 year old woman. Went to see my doctor yesterday because my blood pressure was 154/94 and my pulse was 135. I was also running a fever of 101.2. The doctor diagnosed me with the flu (he said that went a person has a fever the heart rate is higher) - He did an ECG and it was normal. He prescribed me 25MG of Atenolol wich I took the first pill yesterday. It gave me such a bad headache and isommnia that I'm afraid to even take the second pill today. Can I stop taking Atenolol until my doctor prescribe me something else? Remember that I only took one pill yesterday - I need to mention that I no longer have fever and my bp is 105/84 with 97 pulse. Thank you.