Sudden and recurring genitals symptoms, more inside

Throwaway here. As English is not my native language, I'll try to describe in as much accuracy as I can.

My wife and I live in different countries, and every couple of months we visit each other. A day or two after having sex (no condoms, no pills, no lubricants except saliva after oral sex, no un-natural elements at all), we both start to get some symptoms.

For me, it's some white material under my foreskin, right at the base of the knot of the penis. It looks like peeling skin, but it's a bit stickier. The glans itches a little, and there's some redness (not spots, but rather right above the knot some redness coloration, probably because of the itching that I'm scratching). Last time also the skin of my balls sack went dry and peeled.

As for my wife, also a couple of days after sex, she begins having white discharge and itchiness.

The strange thing is that after these symptoms by a few days, everything disappears and goes back to normal. We can both rule out extra-marital affairs. Would anyone have an idea what this may be?