What Causes Dark Color Spot With Bump On Groin Area?

my 86 year old father thinks he may have been bitten by a bat fly...the spot was dark in color and a little bump on his upper thigh/groin area. When he squeezed it out after several days it was black and had a very bad odor...he had been feeling ill, and weak and tired. Someone suggested it may have been caused by whatever bit him. He first thought it was a tick but has ruled that out. He finally started to feel better after removing/squeezing out the area that appeared to be a bite of some kind