Periods for more than 7 days. Disease.

I am a 38 year old having a 3 year old kid. My periods have been irregular since past 9 years due to pcod. But my period has never lasted for more than 5 days. This time as usual I got late periods and it was like other times till the 5 day. But on 6th day I suddenly felt that I am bleeding and I continued to lightly bleed (one pad is enough) till the 7th day . From 8th day onwards the bleeding stopped but I started passing clots every evening with considerable amount of bleeding till today (10th day). After the clot is passed with blood period stops completely for the next 24 hours. Again next day after 24hrs I get clot the same way. This is happening for 3days now (8th , 9th and 10 th day) . I am really worried why this is happening. Will do an usg on Monday but till then can you pls tell me what might be the reason. Since I am going for an usg appreciate if you can tell me why I am getting this. I am very scared that i might get a life risking disease.