I thinking what if it's not a cysts? It doesn't hurt when I touch it. Only when I sit on something hard and it goes into…

I thinking what if it's not a cysts? It doesn't hurt when I touch it. Only when I sit on something hard and it goes into direct contact with the area... it's not soft but firm and under the skin... and it came out of no where... the last time I had a cysts it got bigger over time while starting off small... this bulge has only been here for a week and a half and stayed the same size... any thoughts mamas?