Is this night-guard supposed to feel like this?

I’ve recently been fitted for and been given a night-guard (for clenching my teeth during the night) and it is slightly uncomfortable…

I’m not just talking about the obvious strange feeling of it being in my mouth..I’ve kinda got used to that… but my back teeth and gums seems to throb after having it in for a few minutes. I’m also having more headaches rather than less and have had shooting pains through the gums of the back of my mouth…. In terms of sensitivity that’s gotten a little worse!

Some of you may remember that I’d been to my dentist and thought they were incompetent anyway… so I’m a little more worried now…