Do i need to disinfect toilet seat after use if i have a boil/boils on buttocks? i know they can be caused by bacteria... how much should i worry about spreading germs to others?

If it's a shared toilet in your household, it may not matter much. The bacteria causing your skin infection likely are all over the place, in dust etc; and the same ones often are on people's skin anyway, without symptoms. The risk to the next public toilet user probably also is low. It makes sense to wipe with disinfectant after use, but probably makes little real difference in risk to others.