Around 14years Ago My Partner Was Bitten By An Insect,

Around 14years ago my partner was bitten by an insect, don't know what, when in Mexico; we live in the UK. Since the bite he has a raised white bump/pimple which grows over time and then a little black dot appears, when squeezed it produces a white thick mucus that is foul smelling. It doesn't cause him any pain at any time, but the area does become very itchy at times.