Even an ectopic pregnancy will produce a positive pregnancy test. Pregnancy tests merely test for the presence of hCG, the pregnancy hormone. They do not tell the location of the pregnancy. A home pregnancy test cannot detect pregnancy as early as a blood test, though.
I don't know how long it's been since your period, but you should wait at least a week after your missed period before taking a pregnancy test. If you follow the instructions in the test properly, they are 99% effective at determining pregnancy.
If you are feeling sick and have the symptoms you describe, you should just make an appointment to see a doctor. It doesn't sound like you're pregnant, but you may have an illness of some sort.


