I noticed today that my washing machine as well as my kitchen sink are draining into my sump punp. This has never happened until today

Your sump pump must be tied to the house main. If that's them case you have a blockage downstream from the pit drain.
Snake the drain from there or from either the washer or the kitchen sink roof vent. If you snake from the roof put out enough snake to reach the base and 20 feet more. Good luck, Tom