Itchy Clitoros while on antibiotics

i  am on antibiotics because i had tonsillitis which is an infection in your tonsils and it feels like a really bad sore throat so while i am on antibiotics i realize that four days into it my clit is itching. not my vagina but the clit. my vagina is sore due to the fact that the clit itches. my mother told me this a reaction becausei ate pizza while on antibiotics and as you know your not suppose to have anytype  of dairy product while your on that mediciation...i forgot. so i want do know whats wrong with me. this has never happened bfore i have been on antibiotics before and i had accidentally ate or drank something dairy and this hasnt happened. i do want to say that i am sexually active and im eightteen and my boyfriend and i were eachothers first and i did check online to see if i had an std. oh and my vagina is dry...because when the itching started i washed with summers eve for senstive skin  because i thought it was because of my pee...seeing as i was on antibiotics i thought my pee would be different. but anyways i just put and ointment around the clit for temporary relief and drink lots of water. the medicition im on is amoxicillin five hundred ml pleasseeeee give me info