What Causes Irregular Periods With Mucus Filled Blood?

Hi, my menstrual been very normal until couple month ago. I miss a whole month then the following month I got my period so I figure it was nothing serious. Now again it have happen, I miss the a month and got my period the following month, now I been notice that I been discharging like "jelly like blood", which I believe it uterus linning but I have never seen that it can be that much. Because I have experince that but not so much. My question is should I be worry that this going on?