This is purely natural. Your reflex muscles are gone. It seems that your hard work has been all wasted!
Arrrggghhh....dont be shattered by this. What I have written is NOT really true. Your hard work has not been wasted. Its just that your muscle memory needs to be jogged a bit. Take few more practice tests and you'll be fine.
What is happening to you with Quant is happening to me with Verbal. I took a bit of break, studied Quant for a month and started studying Verbal again, and I see that my accuracy has dropped. Nonetheless, I observed that if I do Verbal from morning till evening, only one out of SC/CR/RC, I will make substantial improvement by evening. So its not gone, its just taking a bit of time to come back.
Final tip here- From now onwards till you take the exam- practice all sections each and every day without fail, even if you have to do few qns. You will be in good shape by the time you'll be taking the real stuff.