It is very seldom due to cleanliness or lack thereof. It sounds like a bacterial infection like BV. This is normally treated with antibiotics. Neither the exam, test or treatment is very expensive. Do you also smell this just before or after your period? During masturbation? Do you allow him to ejaculate inside you?
When did this start? Have you made sure you do not have an old tampon stuck inside (it happens)? Doe you have a normal discharge cycle? Any burning or itching? Any chances of an STD?
Your vagina is a central part of your life. It is a source of life, with fertilization and birth taking place through it. It is also a big part of your sexuality and pleasure. So do not come with the 'please don't tell me to go to the doctors' story. I understand the issue, but that is not the solution, and often not seeing your doctor when you should will only make it worse and even more expensive later.
Find the free or cheap medical resources in your area. There are normally clinics run by counties, your local ER, Planned Parenthood, Student Services (if you are at college) and with the new Affordable Care Act you are also covered by your paren's insurance until you are 26. (if they have insurance). Or see a nurse. Or ask your boyfriend to help, he is after all a big beneficiary of it.
Vaginas does not normally smell bad after sex. And using all sorts of douches can only mask the issues, or make it worse. Once the issue has been identified, there might be something natural you can use.
Best of luck!