For a puppy that young is normal to feel what is known as separation anxiety. Sometimes we contribute to the problem but don't blame yourself 100%. You have two options, either hire a dog trainer who specializes in puppies or find the information online and create a program that meets the needs of you and your puppy. The first step always is to talk to the vet to make sure there are no medical conditions involved. Be careful with websites that offer "free dog training tips", some of them are not maintained by professional trainers and can get you more confused or give you wrong advice. I recommend the Humane Society or the ASPCA websites to find tips for addressing this problem.