Can BV appear quickly?

Hey ladies, I’m 22F and he’s 24M.

so I had sex with guy nearly 1 week ago, hours after having sex I was cramping. So I got canestan Bv gel. It stung getting it in as I had some tears, I started having thick bloody discharge and on and off cramps. So I used this treatment. Today is my last day but I rang up the hospital to get my iud removed which is Kyleena as it causes Bv when I have sex (I’ve never had it until it was inserted) I’ve ordered a std test kit to try out and see if I’m on the safe side. We spoke about our status and he said he was recently tested and I said I was as well and he said he has nothin. So I’m getting little spotting happening and my discharge is stringy and thin. So I know that’s a sign off Bv. I’m just annoyed I have it and the Gel I’m using isn’t clearing it up. So has anyone else has these problems? Still having some cramps but they don’t come as often as the start. Any advice would be helpful.