Thanks for using HCM, I understand your concern and will try to give you my medical advice, I think in effect he has an allergic symptoms I recommend you don t stop the antihistamine medication although you are thinking is not working ( could be worse) and use some OTC eyes drop like artificial tears or descongestant and some cold compresses 3 times/day those can relieve the symptoms, sometimes that allergic process is increased by excess computer use, windy conditions or be awake for long period of time, try to keep a good hands hygiene because you can t avoid that he manipulates his eyes, I hope that my advice has been helpful,take care