You need to go the lab to learn matchup. It happens to everyone. See what your opponent is doing, the especial moves that he uses and check the frame data to know which ones are punishable, gaps, or where you can poke out. Then practice the punishes and then find a good player who uses the character and grind matches. Rinse and repeat until you feel comfortable with the MU. Losing to a new character is part of learning the game.