So I have a foul smell coming from my vagina & m y husband has recently told me that my vagina has an odd sour taste to it . Do you have any idea what this could be ?

It could be a yeast infection but only a doctor can properly diagnose you.

I mean I had uh yeast infection , it was really itchy & burned I used vagisil . It actually made all the itchiness go away .so I figured the whole yeast infection was gone for good . But I guess not . How much do you think a gynecologist appointment would be or is it free

Unless you can find a free clinic in your area, it would not be free. The charge would entirely be based on what type of insurance coverage you have. You can call your insurance carrier to ask. If you do not have insurance, you'll have to find a doctor who will accept self-pay patients. They can tell you approximately how much an appointment and PAP test would cost.

I don't believe Vagisil can actually cure a yeast infection but either way, you can't diagnose yourself and I can't properly diagnose you over the Internet. Follow up with a doctor for the best results.
Good luck