Ominous causes of sudden onset migraines

Within the last 5 days Ive suddenly started having classic migraine auras (flashing zigzag patterns, in expanding C shapes) lasting for around 10 minutes, leaving with a headache behind either eye and either temple.  Had one on Saturday, woke with one on Monday and had two others later in the day, and woke with one yesterday.  Ive never ever had visual disturbances before, and have been lucky enough only to suffer with mild headaches very occasionally.

Im 46 and have recently had issues with my heart rhythm (Supra Ventricular Tachycardia episodes) which Ive been told were caused by an overactive thyroid, so Im now on 120mg a day of Propanolol and 80mg of Carbimazole.  

My doctor thought that the beta blockers were causing the vision disturbances but yesterday called to say that she is urgently referring me for a brain scan to rule out any issues with blood clots causing the auras!  In the meantime I have halved my beta blocker dose to see if that makes a difference, and touch wood Ive had nothing today!

I would be grateful to hear from anyone who can offer an opinion as to why Ive suddenly started getting migraine auras at my age, or have any experience of the same?  

[Dr Santos]

Hi,
How are you? How was the brain scan? There are some studies that relate SVT with migraine. Although it is better to rule out any other issues other than primary headaches like migraine. You may benefit from a referral to a neurologist and cardiologist, aside from your attending physician/endocrinologist managing your thyroid issues. Imaging studies will help determine if the headaches are  indeed from primary headaches only or if they are attributed to organic issues. A headache journal will help identify the possible triggers that you could also avoid. Take care and do keep us posted with the scan result.