I'm v concerned about my vulva. Scared its C

For at least 4-5 years I sometimes experience a mild, dull ache on the right side of my labia majora (outer lip). It almost feels like a muscle cramp and so I've ignored it. It doesn't occur at any particular time in my cycle. It usually doesn't last longer than an hour and it occurs less than a few times a month. Except now I've been experiencing the same pain for 3 consecutive days. The pain goes from mild to moderate and back to mild. If I massage deep into the tissue I can feel that either my glands are swollen or there is a large (approx. 2-3 cm wide, 0.5 cm deep) unidentifiable lump.