Even though you have been with the same person sexually for long amounts of time (1 year, 3 years) does not negate that some STD's lie dormant. For example, HPV can lie dormant for years and years. Also with Herpes, some people have one outbreak and then never have symptoms again. Chlamydia shows no symptoms in woman many times, but is the most common STD worldwide in women.(
Chlamydia infection - Wikipedia, the free encyclopedia)
And remember, just because you have been faithful, does not mean your partner has.
Whether your "bump" is an ingrown hair, a sebaceous cyst, an infections, or an STD, keep an eye on it and always see a qualified doctor as soon as you show symptoms. Getting a culture of the fluid you squeezed out could have helped a doctor diagnose your problem.