I did read Pslam 22 but I still don't understand why...?

...on the cross Jesus said, "My lord, my lord, why have you forsaken me?" I'm told it was to fullfull the prophesy of Psalm 22 but all that seems to mean is that the prophesy predicted He would say this thing that seems to indicate at least a temporary loss or waning of faith. Also, if He was God, why was He speaking to God at all? Can anyone please clear this up for me? Thank you!