Sour vagina, please help!

Ok so tonight my boyfriend went down on me and he hasn't for a while now but he did and he couldn't take it and had to stop after a couple seconds. Because he said it was so sour he couldn't take it. He told me I should stick my finger in it and try it and I did and he was right. Like it tasted like straight lemon/line strength with vagina taste
What could make me taste like that and how do I make it go away?
If it helps, this app said my 'fertile window' starts tomorrow and my period ended like a week and 3 days ago