I think if you can you should see a nurse at your GP surgery to get it checked. Most likely to just reassure you. In the mean time, or if that feels to difficult, put a warm damp cloth/bit of towel (or something similar) on it and hold it there a while. It'll help draw anything out that it stuck. Don't put any chemicals on it, unless they are for the purpose though, else you could end up with an infection. Could be an ingrown hair, some sort of spot or something like that, and probably nothing to worry about. Also try not to touch it too much and keep it clean.