Knee Question, Cracking

All of a sudden, from no cause i can think of, both my knees crack every time i go down into a squat posistion. Not just once, but every single time without failiure. They crack when i make a turn or a quick movement, they basically crack on everything. Strange considering i never ever had this problem untill about a week ago. I went to pysio and a docter and they both said if it dosnt hurt dont worry about it. But isint it strange how it just happens all of a sudden? and to both knees? Anyone else experiance this or know what could be causing it? thank you