5weeks and 6days brown discharge??

Hey Mommas!πŸ™‚ im 5weeks and 6days today and this morning i had some brown discharge, no cramping just mild lower back pain and just brown discharge when i wipe,, i did go to the ER as that is what my OB told me to do since the clinic is closed on Sundays, has anyone experience brown discharge? They also did some blood work and and ultrasound at the ER and said my HCG levels are 3,156 and my ultrasound showed only the sac.. doctor said it was still too early and that i should get checked up again in 3days for my levels and another ultrasound.. has anyone experience this? What were your outcomes? Im not trying to stress out to much but i cant help it.. also i feel like i don’t have a lot pregnancy symptoms or sometimes none, i know every pregnancy is different..