Why do my contact lenses hurt so much ?!

I've been wearing contact lenses for about a year now and for the past 2 months or so, whenever I put my contacts in they absolutely kill. It's like theres needles in my eye and sometimes my eyes go all red. Most days I have to only wear one contact because the other one is too painful or irritated. I put new saline in my cases each day and wash my hands and everything and swap my contacts every two weeks (I have the two week ones) but recently I've had to swap them every few days because they're a lot better if they're brand new. I've even worn glasses for a week to give my eyes a rest but nothing is working, please help !