Irritation or something more?

Hey, so my boyfriend and I have been sexually active for the past few months now, but last week I started having pain at my vagina entrance along with some itchyness. At first I thought it was some irritation from chemicals products in the pool and then Sex with probably not enough irritation, but a week later (of rest let's put it that way) it is no longer painful or itchy , but when he enters it is super painful and we can't do it. There's a little blood particle (like dry, that I suspect are from my period that ended a day ago or so) and basically the stretching hurt very bad, and it just doesn't work. But no itchy or painful peeing. The entrance looks redder than usual. Could it be something very bad or a bit more rest and some lube could do the trick or I should go to the doctor to make sure ? (I am not in my country so if I could avoid the doctor that would be great )