Stopping Zantac (ranitidine)

My 4.5 month old son’s spitting up seems a lot better than in the past. As a result, I have took my first step in weaning him off Zantac. I have reduce his dose of 0.7 three times a day to 0.5 three times a day. I have done this for the past 5 days without any signs of him being in pain.

However, I have noticed that he is irritable, sometimes cries for no obvious reason (although it is not a cry of acute pain and he stops whenever he is distracted), arches his back while he is asleep, wakes often during the night and keeps putting his hand/fingers in his mouth (sometimes sticking his finger so far in he gags).

I wonder whether it is his reflux discomfort flaring up or could he be teething? His gums are not swollen.

Thanks