How does the word of God become the son of God who was always with God?

How can Jesus be the son of God when he's supposed to have always been with God before the creation of everything? 

He is before all things, and in him all things hold together. (Colossians 1:7)

Through him all things were made; without him nothing was made that has been made. (John 1:3)

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A dilemma Christians fall into Jesus existed before the existence of anything? Yet this man is the son of God? If Jesus was side by side with God then how did he become the son of God? The question is how was he created before the existence of anything Christians normally quote: 

 In the beginning was the Word, and the Word was with God, and the Word was god. (John 1:1)

This is a very weak response if In the beginning Jesus was the Word then he could not have existed physically rather he wasn't mentioned, but kept silent upon untill he was spoken of and became flesh ?

The Word became flesh and made his dwelling among us. We have seen his glory, the glory of the One and Only, who came from the Father, full of grace and truth. (John 1:14)

If Jesus was the word to start with then it's normal that he could not have been the son of God  since he's the word of God?. If Jesus was the son of God like Christians claim him to be how did he become the son? How did he come to existence, did God (Yahweh) give birth to him physically or created him physically from the beginning as this would contradict John 1:1 in the beginning was the word?

How does the word of God become the son of God who was always with God? In what way did the word become the son? How does God have a son in the first place? If the word is the son alone  then everything God spoke of should also be his son?

For I am the Lord; I will speak the word that I will speak, and it will be performed. It will no longer be delayed... (Ezekiel 12:25)

Let the whole world fear the LORD, and let everyone stand in awe of him. For He spoke, and it was done; He commanded, and it stood fast. (Psalm 33:9)

It's doesn't make any sense when Christians say God has a son, one would only have a son or child if he wants to carry on his heir, since God is eternal then he needs no heir nor does he give his powers to a creation to carry on for him. Like some business man handing over his business to his Son to carry on his legacy.!

Again if we was going to exclude the word and focus on the Jesus as the son alone one wonders how did God have this son? Did he give birth to this son  by himself or or did he just appear from nowhere? Unless you say son of God is not a literal rather Metaphorical statement.