Hi mama! Headaches in the afternoon during pregnancy ay quite common talaga, especially sa second trimester, maraming of us experienced that, pero better to mention it to your OB pa rin just to be sure, baka dehydration lang or hormones kaya sore na. Try drinking lots of water throughout the day, get enough rest, at avoid bright lights kung possible, pero don't worry na dahil first baby jitters, your doctor will know best kung normal lang ito or need ng extra care para sa iyo. Congrats sa baby mo!