Why doesn't my 2 months old like the pacifier when he got fussy lately? is he teething in such as young age?

Hard to say why.: It's too early for teething. That occurs at around 6 months, possibly as early as 4, but not at 2 months. Have his mouth checked to see if there's something bothering him in his mouth. Are you bottle or breast feeding and is he feeding well? If there's nothing wrong in his mouth or with the rest of him,(have his doctor check) don't worry; it will be one less habit to break when he's older.