Firefox keeps caching old css and js, have to do a hard refresh every time i view the site

I am a web developer, Recently (this week and last) my firefox has been caching very old resources. If i update a pages html, i can see that change on a refresh, but and css or js changes i make do not reflect. Every time i load a site i have to do a [shift + refresh]. Even if i clear my cache in the preferences it will not solve the problem. The only way i can make firefox load the new page resources is via a app called "clean my mac 2" where i have to do a application reset. I do this 5 or 6 times a day and the rest of the time i still have to [shift + refresh] to get the updated content.