am i pregnant or is it nothing?

ok so about a month ago me and my boyfriend had sex we are both 18 and he pulled out just before he ejaculated and lately I've been having very bad period symptoms and my discharge changed and now its thick and sticky and about 2 days ago my discharge changed colour and I put in a tampon, the tampon was covered in blood and after 2 days its stopped and I'm only getting smudges. I have been so tired, I'm stressed and I've had an enormas appetite.......could I be pregnant?