Birth control overdose

I'm currently not sexually active (last time was about a year ago) but I continue to take birth control to help regulate my menstrual cycle and lessen my pain from cramps/nausea and I've been taking them for about 6 years now. However, I've been sooo busy this week that I've forgotten to take it four days! I know I'm supposed to start a new pack in a situation like this but I don't have the money to be throwing away the rest of those pills like that.