If you are late 20s and not fully immunised against mumps beware, be active and get onto it. You do not need mumps as an older person and they have made a come back. You can get information about the disease here, because in school age children it is a notifiable disease and it spreads quite nicely. There is more detailed information here. There is information more suited to adults here. The main thing is to get medical intervention quickly and don't just pass off swollen glands.