If the dog is acting uncomfortable, sluggish or just out of sorts it could be a sign he is very sick.
Check how his gums look? How long has this been going on? Does he act normal other than when he is lying around? Eating, pooping etc?
Sounds a lot like a friend who's dog bloated but I'm not sure how common that is in dachshunds.
You know your dog best, better safe than sorry, I would take him to the vet
Add:
Just found this link
http://www.dachworld.com/sickdogs.htm If you think your dog is experiencing bloat google some more symptoms and check your dog for that. Bloat is a serious issue and requires immediate medical attention
I hope it's nothing but a restless dog but it's good to have knowledge