15-16 month of microteacup chihuahua puppy help?

Your dog is probably sick and should see a vet. There is no such thing as a micro teacup. You have a Chihuahua that is way underweight and it may well have lots of health problems. These so called "breeders" that promote this type animal should be put out of business. These dogs are the ones to suffer from the "breeder's" desire to make a profit.