First off, if you havent had a problem in 4 years you have obviously developed a new one. Check for obvious problems. Downspouts, leaky waterlines-does it happen to be anywhere near where your water service enters the basement? If so you probably sprung a leak. Have your neighbors recently done any grading of their lots or a new home been built?That can change how runoff flows in your neighborhood.If you have clay soil, was it dry the last few years and it started to rain this year? The clay will shrink away from the foundation providing the perfect channel for water to get next to the walls.Definetly explore the easy fixes before spending a bunch of money on fixes that might not truly be needed.