A headache starting from neck tension, growing worse with movement and talking, and easing with rest usually points to a tension or migraine-type headache rather than a structural problem. It's reasonable that you stopped the medicines once they caused drowsiness and low mood, since those are known side effects of some headache preventives.
Next Steps
Don't restart or adjust any of these medicines on your own. Go back to your neurologist, describe the mood change and the trembling clearly, and ask about a different option with fewer side effects. Completing the MRI and blood tests he suggested is still worth doing, since that rules out other causes independent of the medicine decision.
Health Tips
See a doctor sooner if the low mood deepens, you have any thoughts of harming yourself, or the trembling episodes repeat.