Penis foreskin itching, redness,

I have been experiencing itching, redness and little swelling of penis foreskin. It has occurred 4-5 time in the past 6-8 months. It goes away in a day or two. Till now I have not used any medicine or ointment and it gets treated by itself. I usually ensure good hygiene by bathing regularly and clean the foreskin at least on alternate days. My diet doesn't include very spicy or oily food. One peculiar thing is I have started eating a bowl of curd everyday morning.  I don't know if that is causing this. As far as sex life is concerned, I indulge only with one partner and use condom as contraceptives. My questions are:  Is it serious or it's common? Can it also be caused by using condoms(although it's not like it occurs only after having sex) and most important question is which ointment to use when it occurs again?