Ticks do not usually bother dogs, they just fill with blood then drop off. If the lump is bothering her, then it is probably either a cyst or an abcess. If it is a cyst then the vet will either decide to remove it or leave it alone, if it is an abcess it will either burst or the vet will drain it.
Ticks start off looking like tiny little deflated hot water bottles, then as they fill with blood as the tick sucks it from the animal, they get to the size of a currant, although they will probably have dropped off by then.