What a guard does
It puts a layer between your teeth. That is genuinely valuable. Enamel does not grow back, and a cracked molar is an expensive night. Keep wearing it.
What it does not do is tell the muscle to stop. Plenty of people clench just as hard with a guard in, and some clench harder against the new surface.
So why does the ache change?
Often it moves rather than leaves. Less tooth pain, same temple tightness. That is the tell that the remaining problem is muscular, and it responds to manual work rather than to more dental hardware.
Bring the guard to your first session if you have one. Where it wears tells me which side you load.