Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with a doctor.
Without the ability to examine and obtain a history, I can not tell you what the exact cause of the symptoms is. However I will try to provide you with some useful information.
The first question I have is do you have a history of headaches or migraines? If so, is this different from your prior headaches?
The symptoms you describe of pounding and being unilateral are both features of a migraine. If you have any nausea or vomiting or light and sound sensitivity, I would say it was a migraine or probable migraine just by your history.
Going back to the initial questions I had, if these are different than your prior headaches, I would suggest that you be examined by your primary care physician.
Without additional information, it is difficult to provide much more information, but I would suggest that you follow up with your primary care physician.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.