possible miscarriage

I just had a baby 9weeks ago . Well me an my husband had sex when I was 3weeks post partum, (I don't need to be educated about waiting 6 weeks ) anyways I only bleed for two weeks after birth then went a month without a period , then started July 4 (happy independence day to me lol) and have been bleeding since but I've noticed I've had some bad cramps,migraines , back pain and some stringy like clots and today when I got ready to take a shower , (i pulled out my tampon) I noticed this clumpy looking clot , and I got to staring an think maybe I am experiencing a miscarriage? Or maybe it's the lining of my uterus still cleaning but here's a picture and tell me what you ladies think . I go Monday for blood work because I'm suppose to get my tubes tied the 26th .