I am sorry to hear that your symptoms have been so worrying for you.
Firstly, your symptoms sound like what we refer to as Intermenstural bleeding.
In a young person of reproductive age like yourself, the main thing to always rule out is always a pregnancy whenever you experience irregular spotting or bleeding that is out of the ordinary.
However, if you have not been sexually active, then there can also be many other causes of intermenstural bleeding such as cervical polyps, infections or even hormonal imbalance.
My main advice for you is to go see a doctor regarding your symptoms so that we can better investigate the cause of the symptoms to ensure this is not caused by something serious!
Hope this helps!
Dr Michelle Chia