Please help my scalding skin!

My shower has recently started turning scalding hot all of a sudden and staying that way, regardless of how much I turn the cold water tap. Often it happens with a pressure reduction (presumably cold water turning itself off for an unknown reason), but not always. I have to turn the hot water all the way off (with cold on) before it slowly cools off. It doesn't seem to be associated with other water sources being on (although I do live in an older apartment, so maybe the neighbors?), and the fact that this phenomenon just started makes me think it's not others turning on the water. The water has always fluctuated slightly during my showers, but this is insane. Is it possible that the cold water valve is broken and randomly sticking shut? Any suggestions on what it might be (and how to fix it)? Thanks.

cw

Not necessarily broken, but the washer on the end may be loose and shutting off the water flow until you turn it off and then turn it back on.