Hello, Thank you for writing at HCM. If you have a painful bump that you noticed within one night it means that very likely it is an abscess- which is a collection of puss or some kind of local infection. There are also pilonodal cysts that may cause tender bumps in the buttocks but they tend to effect the area between buttocks mostly. This is a collection of puss but is deep and might not be enough with just simple draining but might need surgical drainage and removal of all secretions. If you have no fever and not feeling tired and sick generally (which speaks of more serious infection) you can try this: Local warm compresses are helpful (10-15 minutes 3-4 times a day- watch that you do not get burned) to help with more blood going to the area and localization of the infection and in many cases this is enough for the bump to open in the skin and drain. Pain killers may be used to help with pain: paracetamol and Ibuprofen. Very likely if it is an abscess it will open and you will have some relieve. If no improvement with local warm compresses and pain killers for a couple of days than it is good to see a doctor for definite diagnosis and treatment. If you have fever and feel unwell you will need to see the doctor soon. Hope this answers to your question and is helpful for you