Oo, normal talaga yan especially sa first trimester, mama! A few of us went through the same thing, ang sikmura talaga sobrang unpredictable, minsan tumatagal ng ilang minuto lang, minsan buong araw, pero usually nawawala rin talaga like you're experiencing. Just make sure you're eating small frequent meals and staying hydrated kasi sometimes yun ang trigger, pero if it gets really intense or di na nawawala, that's when you talk to your OB para sure lang.