I had this exact same thing happen to me early in January. 345x5 was alright week A, week B 350x1 is atrociously difficult. Eat and sleep probably had alot to do with it. Had to learn to accept failure, and keep going anyways. I changed my programming from 5/3/1 from then on, so I can't give any advice about staying on 5x5 programming for linear progression.