Should I go to the doctor?

My period was 8 days late, then yesterday I started bleeding it quit like 30 min later and before I went to bed I started spotting so I put a tampon in and used a panty liner this was about 2am at 7am I changed the tampon and went back to sleep, when I woke up at 10am I was soaked in blood (it was all over my pj's), im having constant pain on my left side, the blood isnt the same color as my period what should I do? What do u think it is?