Is it supposed to be like this?

I need to call my dentist. I got my night guard last wednesday. I've been wearing it every night (except for one when I passed out reading). I've still had a couple of headaches. When I first got it, I couldn't bite down on it cuz I gagged when i did. But after a couple of days I got used to it and I can bite down on it. And from what they told me, I'm not supposed to be able to. Or not with much force anyway. It was supposed to separate my teeth enough so that when I did clench down, i wouldn't be able to bite down with much force at all, which would alleviate the strain I'm feeling in my head and neck. So i have to call the dentist and ask about that issue. I have to get some more prescription toothpaste too, so I have to go anyway this week After I get paid.