Blood clots

Hi ladies, I had my baby 12 days ago and the first week of postpartum I didn’t have much bleeding. However, this week I have been bleeding more and I passed a blood clot just now. It felt and looked pretty big in the toilet (it passed as I sat down), but I honestly cannot say if it was the size of a golf ball or bigger. I’m not sure what I should do here? I know if I call in to Kaiser after hours they will not get back to me until tomorrow. I’m a bit worried if waiting until tomorrow will be a bad idea? FTM here so I’ve never experienced this before.