Need a little help

I am a little over 9 weeks postpartum and EBF. My bleeding stopped around week 4/5. Starting a few days ago, I had a little bit of light pink blood when I wiped. Then later that day it was brown. Only a very small bit, I have had it off and on for a few days now. Today there was very stringy brown/yellow discharge with a small clot attached to it. We have had protected sex a few times. Also my sides and my lower back hurts and is very crampy. I have an appointment on Tuesday (earliest I can be seen over here in South Korea) but was curious if this is left over bleeding or possibly an infection. Thank you