I have the same thing on the right side, this is the first time I am seeing this. I haven't been to the doctors yet, but I have a physical coming up. Its not painful like that but it is there and its small. I have another one that was the same size but is decreasing and its been 3 days. I got tested and I came back negative and I am not sexually active like that its been awhile. I believe it has to do with a female's cycle and the reaction to the period. Mine is on the right side and isn't red its skin tone. When I get it check out I will report back.