Help!!! Spotting

Ni

Hiii ok so im 17 and i have been on the combined pill since january of this year. during that time i have been on 4 or 5 different pills because of bad reactions. The pill i am on currently is working fine i feel fine excpet i have just started spotting? i’m not sure if it’s spotting or just brown discharge. i have been on this pill for 2 periods and this is the first time it has happened. i had my period 14 days ago so the brown discharge / spotting is very mid cycle. i’ve never had this before. i’m sexually active however we were both each other’s first time so i know he is safe and he isn’t cheating on me.

Does anyone know what is happening? is it normal? i take the pill at the exact time every night without fail but i’m worried there could be something serious going on. i spoke with my doctor who thought it may be an STI however does also believe to continue taking the pill until i finish the packet, get a period and see if it happens again. Can i get an STI if we are each other’s only partners? i’m not entirely sure how this all works.

any advice would be appreciated