Have Painful Bowel Movements, Nausea, Pain And Swelling/bloating In Abdomen Area. Irregular Periods. What Cn Be Done?

I had a D&C in 2008. since 2010 I have been trying to get pregnant and have not been able to. I have painful bowel movements/constipation, nausea/vomiting, pain and swelling/bloating in my abdomen area and my lower back and thighs(it comes and goes but it is usually present right before and during my menstrual cycle), irregular periods(not ever the same in length of days nor time between, I can never predict how long or when or flow), I spot in-between periods, and few other symptoms. They seem to be getting worse with time. I started my cyle two weeks late, but on the 11th. on the 13th I went to change my tampon(was feeling cramps like usual) and there was a piece of what looked like skin. it was about palm sized looked like chicken skin. vieny. I went to the er and they didn't do anything. I came home and did some google research, I learned I think I discharged endometrial tissue. all my friends and all the quizzes I take all say endometriosis. I was just wondering what is your medical opinion...I could really use one. scared not knowing what is wrong and what to do.