4th Week Slump?

Is there such a thing as a Week 4 Slump? I'm starting to get the feeling I'm never going to improve past where I am now. When will running get easier? When will I be able to run more than a mile without having to walk or feeling like I'm knocking at deaths door? Will I actually be able to swim more than 50 meters...ever?? I figured in 4 short weeks I'd be leaving people in my dust and not always the one eating that damn dust. I wonder if this is the time where people either become Triathletes or become quitters...