May25 I only had my period for two day. Took a pt and it came out negative. Been feeling sick for the past 3 weeks. Should I take another pt and when.?

Yes. Please consider another pregnancy test now. Good luck.
Check and see doctor. Check another pregnancy test as it will be positive by now if you are pregnant. See your doctor either way.
Yes. Even if you had other periods since may 25th, you may be pregnant. Reliable results depend on timing of test after a missed period and test reading accuracy. Without birth control, conception is more likely. Pregnancy signs: breast changes, nausea/vomiting, fatigue, frequent urination, abdominal discomfort. Do a blood test. It turns positive before a urine test and estimates how far along you are.