I would recommend going to see your primary care doctor
about this issue. Although there are many different causes of headache
, the fact that this started after bumping your head in the car suggests to me that that is the potential source of the headache that most needs to be investigated.
In particular, I think it is important to rule out a concussion. This is a mild injury
to the brain which can occur after a strong blow to the head. In addition to headache, there are often other symptoms as well, which can include sleepiness, trouble with concentration, dizziness or visual changes, and nausea. Although the treatment for most concussion is supportive (meaning that you may take pain medications and try to rest), it is important to be diagnosed, because sometimes the symptoms can be more severe or may persist for a while, leading to trouble performing at work.
Your primary care doctor will be able to perform a complete neurological examination and help you decide whether this is indeed a concussion or just a simple form of headache. Either way, they'll give you advice on what medications to take for the pain and will be able to provide follow-up if needed.