PLEASE HELP - scared 16 yr old

I got sick in May due to lack of nutrition and sudden loss of weight. The medication my doctor gave me caused my vagina to act up. Starting June 3rd - June 9th, I randomly started having down brown discharge (SORRY FOR THE TMI) usually, my periods are regular and last exactly 6 days. Now, my period was regular and I got it July 2nd - July 8th. But in the 19th, the brown discharge came back. Following it was light fresh blood that is not a little heavier. It's been going on for more than a week and I'm not quite sure what is going on. I plan on making an appointment to get checked out, but I'm just curious as to what is happening and if someone could help me not stress out so much over this. I am fairly young and always have sex with a condom, my boyfriend has put it in without a condom just two times but only for a few seconds just to see what it's like. The last time I had sex was the 18th (with a condom), a day before this all started.