My sons heartbeat has been in high 160s

I got another ultrasound at 15 weeks and it was low 130s. Is a big drop like that okay? Ultrasound was Monday. Today (Wednesday) I have had more discharge then usual and brown colored. Stretching maybe? Anyone have that too?

Worrying cause the heart drop and the brown color being so close worries me. I have had other miscarriages so I think I just worry. I feel off today.