Here is your answer then. Until last week you were doing no acceleration and no top speed work. Even if you were a 200/400 guy you would need more speed work in your training. Try three high intensity days per week, and do some starts at the beginning of each one of them. One could be dedicated to acceleration (20-60m sprints from blocks or various other starting positions), one to top speed (flying sprints, easy-fast-easy, fast-easy-fast ,etc.) and one to speed endurance (sprints between 100 and 300m). Your other two or three days could be tempo days. Lifting should be done on the high intensity days after the track work.