What Is The Reason For Sudden Delay In The Periods?

i m 30 yrs old ,height is 5'4" and weight is 57 kg, 10 days before my period date there was some brown spotting for 2 days but it was not continuous.After the spotting i got vaginal infection then i consulted to gynacologist ,she gave me medicines for the infection and she told me to take gynaecosid on 25th as my periods did not appear on 20th. Now that i have taken the gynaecosid there is no period uptill now (30th July). My pregnancy test is also negative. i did the last test on 28th.One more thing to mention is that i never missed my period in my whole life. Pls guide me wat shud i do now?