Pimple on lip

I have something that looks like a pimple on my lower lip.  It's on the outer regions of my lip but not on the skin.  It didn't start with tingling or itching, it is totally painless and isn't open in any way.  It is, essentially, just a small bump that is a slightly different color than the rest of the lip (lighter).  It developed two days ago and might be a touch smaller today (although I may be imagining it.).  I know you can get pimples just around your lip but I didn't know that you could get on actually on the lip.  I don't think it's herpes, it didn't start like herpes generally starts and is not a cluster but just one small bump.  Is this possible?  I just want to know how to treat it.  Thanks!