That sounds like a cleft palette to me.
Open his/her mouth and see whether everything appears normal.
Prognosis is extremely poor for poor kitties with cleft palettes. Sadly we lost two, from two different mums and two different dads within two days because of just such a deformity.
If the palette is deformed the best thing you can do for that little kitty is to take him/her in to be put to sleep.
