I've had pain in my groin for about 1yr. What could be causing it? There's no lump or bump so it can't be a hernia, can it?

Hernia? Muscular? Both hernias and pulled muscles in the groin may cause pain in the area you are describing. In general, a hernia is associated with a lump as well. However, a subtle hernia may occasionally be difficult to identify. I recommend scheduling an appointment with a general surgeon.