Boils inside the nose form in a similar fashion as boils inside a cavity. To put you at ease, you should be aware that these are not the most unusual things to happen. Boils are fairly common and can be taken care of quite easily as well. It is not always possible to know why they are caused, however. There could be a huge variety of reasons that lead to boils. These could stem from excessive body heat, a general reaction to a change in temperature, and also go to being as obscure as a hair pulled out from your nose without you realizing it. Since the inside of the nose is a delicate area, if you have managed to pull out a strand or two of hair from inside it while cleaning, you could very well have developed a fairly painful boil. There are a few things you can try at home to get rid of the boil, but please keep in mind that there is no definite cure for it. The remedies may be able to provide you with relief, but they may not necessarily be instrumental in getting rid of the problem. Also, there is no guarantee that there will be no recurrence of the boil.
If you have suffered from this condition for more than a couple of weeks, you should see a doctor and follow his advice. It is entirely possible that you have developed an infection of some sort that cannot be easily cured using home based remedial measures. The first thing you need to know is that picking at a boil is a complete no-no. All this will do is interfere with the healing process and probably worsen the pain. It is not always easy to not pick at a boil or some other such inflection in the body, but it is important to do so. If you have a scab, you need to wait till it dries over and falls off on its own. Application of anything greasy to your boil will help by not keeping it dry. But please make sure that there is no open skin anywhere on or around the boil. Otherwise, the grease will form a layer around it and not allow the open skin to heal. Make a mixture of a bit of rose water and sandalwood powder and apply to the boil. This will be very useful in healing, particularly if you are suffering from a heat boil.