Your dog has chronic kidney problem and for that your vet has prescribed nefrotec ds2 tablets daily one since six months, which controls kidney damage, so continue further.
You should not give him heavy food containing high fat & protein. Light diet like gruel of ragi, rice, wheat, rave should be given, with butter milk, soya milk also. Fruit juices, give perinorm injection which also controls vomition & then give ranitec orally 8 hourly. Give liver tonics like liv 52, or livobex orally 10 ml twice a day, imferon inj or its capsules
with folic acid will help to build blood in the body. Sgot & sgpt & esr tests to be made to know the health condition of your dog. You should keep daily observation and make note of it. If vomition does not stop, take him to veterinary hospitals for iv fluids & further treatment for vomition.