Suggest Risk With Water Sacks Inside The Skull

Hello my name is Marily.. its been about a week that i been getting really bad headaches. I had hit my head about 6yrs ago & im scared it might have something to do with that? been to the doctor they say its just stress that im going threw but I dont think stress feels this bad or does it?? the first time I went to the doctor they told me I had a sac of water outside my skull is that bad?? do I need to get it removed??