Pregnant but pregnancy test was negative

ask ko lang po my friend was pregnant daw but she does pregnancy test kit multiple times but it was negtive nag spotting sya last april 12,13 and 15 pero it only last a couple of minutes only. Ano po need nya gawin to know if she is pregnant or not medyo bother na din sya kase going 2 months na daw po syang di dinadatnan? Please any opinion. thanks. just helping my friend by the way.