What Causes Vaginal Itching After Intercourse?

Hi, I ve been noticing white chunky build up inside of my vag, I ve been tested for STDs which came out negative, and for yeast also which I didn t have. I did have Gardnerella at one point but I got rid of it and I still have this strange build up growing. I am sexually active, and whenever my partner and I do anything he tends to get itchy afterwards, he also has told me about getting a rash around his foreskin, even though I don t get itchy afterwards or feel any sort of discomfort. Him and I never had these problems before until we split ways for a while and found different people, and when I was with the person I was with I didn t have anything, nor did my partner at that time transmit anything to me. Any recommendations of what it could be? Thank you.