my mom broke my mouth guard :'( what can I use until I can get a new one?

My mother broke my custom made splint (or mouth guard, I'm not sure, it's those plastic clear ones for the upper jaw) last night and i'm devastated. My dentist is on summer leave for 4 weeks, so the next appointments are in a month minimum.

It's a specific splint where they measure your face, jaw alignment etc. (which was really expensive, too. It's called Geschtsbogen in german, couldn't find a proper translation) on top everything, and it's the only one that helped me in 7 years. I've had it 1,5 years and it helped me greatly and now im terrified - because before this splint I was in a lot of pain and suicidal. It apparently cannot be put back together (in my head that seems like such an easy thing to do, i'm not sure why it's not possible, even temporary).

What works well as a temporary relief, without making things worse/ altering your bite until I can get a new properly made mouth guard? Am I better off not using any splint at all?

I am terrified I will go back to the land of agonizing pain, and ruining my teeth further in the next 4-6 weeks it'll take to get a new splint. My lower jaw/ teeth also pushes against my top incisors when I sleep and there's so much force I'm scared I'll break them without a splint. Usually I get notable tension and pain if I don't wear it for a day or two (it usually take 3-7 days of wearing it again after forgetting it once to slowly go back to baseline pain levels). I already have other chronic issues and I can't do this again.

I feel a bit insane because this is just a short period right, big deal? But I guess a lot of you also know how much of an impact little changes can have. For better or ... for worse. So I'm just scared. I'm located in Germany, so I assume some online products won't be available to me. I appreachiate any OTC options/ advice/ opinions/ ideas. I've never been in this position before. Thank you for your time.