shifter problems

hi, i was driving home today, i was going from 1st, then 2nd, then when i went to shift to 3rd my shifter didnt go in, then after alot of high reving, 4th gear, and back to the future neck jerks i got the car to a decent speed. when i got home i parked the car and went throught the gears and they arent going through as smooth as they used to be. i have only had the car for like 2 months. any ideas of what the problem could or is it that i just cant drive. i hope its the latter.

thanks in advance

Does the tranny grind when you try to shift it into third, or just refucse to engage third gear?

um, it doesn't make any noise, it just wont go into the slot, it feels like there is something in the way. i dont know if that helps but i hope so.