Spotting

Molly
So I had my period on June 4th, which my periods are irregular since I had my son. Well on the 17th of june I had spotting and I was worried so I made a Dr appt, my home tests and test at Dr office were all negative so she prescribed me birth control and the spotting stopped, well it made me sick so I quit taking it and after 2 days started spotting again. It's only there when I wipe just find it odd. Not sure if I should be worried. Could it be serious? An infection maybe? Running out of options