Hi, Three Days Ago I Sat For To Long On

Hi, three days ago I sat for to long on a hard wooden bench where after a while I could feel my hip bone on my left butt cheek. Know my butt cheek is very soar, swollen, hard, hot, red and feels like I have a lump inside. It's very painful to sit, walk and lye on my back.
I m 7 months and a half pregnant. What do I have and what should I do?
Thanks