The only way to clarify your doubt is to get a serum beta-hCG
titre estimate as a HPT may not read well in your case. The blood test
is sensitive as well as specific and if needed, you may also get a trans-vaginal sonogram. If pregnancy
is excluded through the blood test, it is likely that you had a delayed period and a plug of cervical mucus discharged. Please see a specialist for a physical evaluation and further management. Wish you good health.