Spotting Brown Discharge

15weeks pregnant po ako . april nag positive May everything is normal pero yong june 1time nag spotting ako red yong color nya then by July 3x ako nag spotting pero ma brown yong color nya so nag pacheck up nako nun resita si doc pam pakapit only for 5days lang yon . And then Aug10 nag spotting na naman ako ng brown . Bakit po ganon ? Idk 1st time ko lang po.