If you look in at the base of the lump, you may be able to see legs sticking out, if its a tick. Before attempting to remove it, either soak it and the area around it in alcohol, or cover it in vaseline or similar, both of which will encourage it to loosen its grip before attempting to remove it.
It's important to remove the entire tick, including mouth parts etc, as anything left behind is liable to cause infection. If you are not happy to do this, a quick trip to the vets is called for