Veterinarian needed!?

My Dachshund is really sick. Hes been throwing up everything that he eats. he hasnt pooped and hes lost tons of weight all in one weeks time. Took him to the vet. They took xrays and bloodwork. bloodwork came back normal (twice) and said there looks to be something in his stomache. did the surgery. nothing was found in his belly or intestines. he is still throwing up and loosing weight. he is about 7lbs now. I am going to find a diff vet to ask whats up with him but is there anything that they should specificly look for? they tested for Parvo but he doesnt have it. i knew that. he cant keep anything down and wont p anything either. hes on 4 diff meds and perscription wet food. i am really worried about him but our vet is being real shady with me. i dont know what to do! The dog looks awful and has no food in him at all. im pretty much desprate for 3rd, 4th, 5th opinions!!!! please Help! hes only a year old, and hes starving to death and the vets taking her time getting back to me.