Why does head hurt if you miss 2 or 3 days of you anxiety meds, or could it be from hitting head with sharp object?

Just like hangover: Some anti anxiety control the release, the reuptake or let's just say the activity of nerve chemical transmitters and that balance of activity is skewed after not taking the medicine, just like after drinking alcohol and the alcohol effect is going away. Some others are controlled meds and can cause tantamount to withdrawal. This is a simplistic way of explaining it.