I am 34weeks an I had thrush formally known as yeast infection an my doctor gave me Monistat7 but my insurance didn't cover it so she put another prescription in for Miconazole7 which is the generic brand for Monistat7. You can get the antibiotics for it but most doctors don't want to take the risk unless it's a harmless antibiotic for it but most recommend the Monistat7 or the Miconazole Nitrate so just ask you're doctor
If you're in your 2nd trimester or further then there are options. I'm not sure what they are called, I'm from Australia and everyone on here names different brands to our products.
Otherwise I'd also advise taking probiotic tablets (good bacteria) thrush occurs coz antibiotics kill all bacteria, good and bad, so probiotics help to balance things again