Headache is a known side effect of the Domperidone. Please see the resource for the side effect;
Sensitivity and light too may be responsible due to it as it is a cause of effect relationship. Since headache and this symptom started together; both of them can be traced to medication. An irritability is a known side effect of Domperidone.
Please feel free for your follow up questions.
I stopped taking it in June. It can't still be in my system - so that would make me think it has compromised my central nervous system?
Medication is not likely to be in your system now but sometimes lingering side effects/untoward effects can stay for some duration. These symptoms may have other aggravating factor like your other medications, concomitant medical conditions etc.
It is privilege assisting you.