(PIC WARNING) Concerning Discharge

ayeare

I am currently 18 weeks pregnant. I was diagnosed with a full placenta previa a little over a month ago and have been bleeding on and off my whole pregnancy. I haven’t bleed in a little over a week but have been having very strong cramping the past two days. I went to use the bathroom and had a fairly large chunk in my underwear. It’s larger than my first knuckle and if you zoom in it looks like some weird tissue? Due to my placenta previa I’m worried this may be something to do with my cervix? I have a drs appointment in exactly a week but I’m now super worried. Any advice? I can’t find pics of discharge like this online anywhere it’s solid, not liquidy or stretchy