What Causes Excessive Vaginal Discharge Along With Burning Sensation?

Hi am having a problem I notice for about two weeks now I notice some white/clear liquid running from my virgina and that was after I have sex with my bf and we don t used condom and then I notice i started to experience itching and burning and my clitoros is tender but then two days after I notice the discharge is now brown I haven t seen my period last month but sometimes it skip months but it haven t done that in a long time I feel really uncomfortable if my panty gets wet I have to change it cause its like it s irritating down there its just sensitive and when I use soap to bathe it burn my Virginia please tell me what s wrong but the thing is am taking some medication for acne deriva c gel and apo doxycycline capsules so I need ur help.