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 your doctor.
Without the ability to examine you and obtain a history, I can not tell you what the exact cause of your symptoms is. However I will try to provide you with some useful information.
One-sided pulsating headaches are most often due to migraines, which is a primary headache disorder (a headache disorder without a specific underlying cause). Symptoms last on average a few hours and are often associated with light and sound sensitivity, nausea, and fatigue. In this case the migraines would most likely be unrelated to your cyst. Migraines are treatable with specific medications that are usually very effective. Another possibility are tension headaches, which may in part be related to stress related to the recent diagnosis of your cyst, or otherwise.
However, in someone with a brain lesion, depending on its location, one concern would be for what is termed increased intracranial pressure. Our brain and the fluid that bathes it (CSF) is contained within the skull, which is non-expandable. If there is something in the brain taking up extra space, such as an expanding cyst, or obstructing the flow of CSF (leading to blockage of the CSF flow), then an elevated pressure can occur in the brain. This can be associated with headache, and projectile vomiting. Please understand I am not trying to imply I think your cyst is causing increased intracranial pressure, I do not know the nature or location of your cyst; if it is a simple arachnoid cyst in the typical location, increased intracranial pressure is unlikely to occur. Having said that, if your headaches worsen, you experience morning headaches or headaches that wake you up out of sleep, and unexplained vomiting, then immediate evaluation is warranted. Continued follow-up with your physician is recommended.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.
Call your doc and tell them you are having more symptoms and you do not want to wait until JULY. I would think that the office would have some type of compassion and understand that you are frightened, etc. Never know till you call and find out.