We constantly just get hot water when we turn on the cold water. If you just turn the could knob it starts warm and gets REALLY hot. The more you run the hotter it gets.
Could someone have played with a knob at the hot water heater or on a pipe?
This is REALLY bad in the shower/ tub!!

You probably have a crossed pipe,

Oor your hot water heater is acting up.

Hire a repair man, this isn't really a do-it-yourself job