you haven't teethmaxxed yet!?
use sensitive toothpaste. the main abrasive is silica, ideally you want one without it. this chart is a good reference.
BR | Organic Toothpaste is the lowest abrasion toothpaste available with a Relative Dentin Abrasivity (RDA) level of 12. That means our toothpaste is only slightly more abrasive than brushing with plain water.
essentialoxygen.com
also brush thoroughly but not too firmly, but not right after eating. give it a good 30 mins or the enamel will get brushed away. obviously floss thoroughly and frequently.
ideally you want to salivate to coat your teeth in protective saliva prior to eating acidic/sugary foods, but this might happen automatically.
i recommend using tooth mousse every couple months. you can also get a high concentration fluorine toothpaste without a prescription to use every so often in conjunction with your normal toothpaste.
but if the sensitive toothpaste doesnt fix you issue in the next few weeks, i guess you might have a cavity youll need fixed. are you sensitive to cold water and ice cream?