Yeast infection

Ok! I wrote about my experience at the beach in nyc and I think that it he salt water effected my vagina. I’m experiencing itching near my opening , and last night my vulva (I think) was a little red. Or is it supposed to be red? I don’t think it’s an std because my partner would have symptoms too , and I’m not experiencing anything else but itching. Could it be a yeast infection?