Hello, I am sorry that your baby is not feeling well. I would have your babies anal glands checked to see if they need to be expressed. Alot of times when the anal glands are filled or impacted dogs will refuse to wag their tails or even let you touch the area. This maybe your problem. I am sending you a link to some information on anal sac disease and how to express them yourself if you would like. If you feel uncomforatable doing it then you can take him to your vet or a groomer to have it done. You should also consider having him check by your vet for any kind of spinal injury. Dachsunds are prone to spinal problems. A good x-ray and palpation by your vet will help determine if he has a spinal issue. Once that is determined you should be able to get him on some medication to help with the inflamation and pain. I hope this helps you some but if you need anything else be sure to let me know.