I had an arachnoid cyst removed in 2005. I had a seizure as a result of the cyst pressing on my brain. At the time I had no knowledge on what my condition even was, I just went with what the dr. Said and had it removed within 5 days of finding out it was there. I do wish I would have researched diff. treatment options before I just let the Dr. cut out part of my brain. It seemed to be a great fix at first but several years later I am still dealing with symptoms:( You def. need to get it checked out it can cause serious problems if you just let it go. As far as having it removed I hear there are less invasive procedures you can have done. I would say the least invasive the better.
It depends on where it is, from what I have read. (remove spaces)
http://emedicine.medscape.com /article/336489-overview
It seems that if you have symptoms, they should be removed. I hope you can find a doctor to help you.