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The appearance of a red welt on vagina and tiny lesions on penis in presence of a history of unprotected sex should be investigated for genital herpes, which is a STD. These lesions may or may not itch. The other STDs which should also be thought of are chancroid, syphilis, molluscum contagiosum, and venereal warts. Hence a STD panel should be done for both the partners.

It can also be allergy to the latex of a condom if you have used that brand for the first time. Since both you and your partner have lesions on your private parts, it is important to rule out STD first.

Since a confirmed diagnosis cannot be given on net please discuss these possibilities with your doctor once. Hope this helps. Take care!