Contantly feeling sick

So I’ve had the nexplanon for almost 3 full years. I’m supposed to get it replaced on august 6th. Me and my boyfriend have sex regularly and I let him cum inside me. The last week I’ve had bad heartburn which makes me feel sick and a headache. I’ve just felt overall not good. My period should be coming up in the next two weeks. I normally don’t have these symptoms but I do get heartburn every once in awhile. Should I be concerned that I’m pregnant or is it just me PMSing more as a result of less hormones being released into my body? TIA!