Redness & , painful frenulum - advise needed

can anyone put my mind at ease? ive booked for an sti test but i hope im being over cautious. had sex around a week ago and all fine (protected). had sex with another partner on sunday and since monday ive had a tender frendulum. my penis head under my foreskin has not started to look a bit red but not sure if its down to me rubbing it due to the painful frendulum. am i ok?

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