On and off burning sensation

So I’ve been having an on and off burning sensation sense the middle of June. I have noooo idea what is going on down there and I’m literally going crazy! I called ob and she prescribed me uti medicine sense it was a Friday and wanted me to have it for over the weekend and come in that following week we’ll I finished the medicine and felt fine, we’ll they checked my urine did a swab test and sent it to the lab for uti, yeast infection, chlamydia & gonorrhea everything came back negative. Well the burning started up again! Called ob again gave me a double dose for uti well I found out I was pregnant and the medicine wasn’t working went to my family dr because I needed another opinion she looked down there and right off the bat said I had a yeast infection told me to take monistat 7 I missed 3 days but took it the next night after I didn’t take it, we’ll the burning went away for a couple days and came back, went for my 8 week ultrasound a couple weeks ago and told them to check once again did swab test and urine everything came back negative! HOOOOOW!?!? I literally burn for a couple days and then fine for a couple day’s then burn again off and on I am so tired honestly it’s messing up my sex life and I’m scared sense I’m pregnant I have no idea what to dooooo!!! I don’t know if this has to do with anything but I did have a miscarriage the end of May they checked everything after and I was good to go so idk.

Can anyone tell me what I can do or what’s going on?? I’m not itching or I don’t have the urge to pee with nothing coming out it’s just constant BURNING! Please heeeeelp😭😭😭