Sakit sa puson 2nd trimester

sakin po mommy is sumasakit din pero minsan lng and lasts only for a few seconds then nawawala minsan sa right side or left side ng pelvic area ko. 18 weeks na me now and minsan sa may bandang pusod na sumasakit. I think it is normal basta bearable and nawawala agad. if not get checked po baka threatened abortion na po