You probably can take acetaminophen (Tylenol). But be certain that you don't exceed the doses specified on the bottle. Women with liver disease such as chronic hepatitis should consult with the doctor or midwife prior to using acetaminophen.
Now that you are pregnant, do not take any other medications for headache without calling your doctor or midwife first.
Call your doctor if you cannot get the head pain under control or you start to have nausea and vomiting.
There still could be some other reason for your headache.