Very confused!

Up until July, my periods were on time and predictable. Since then, me and my SO have been trying to get pregnant. But something strange has been happening...I've started skipping periods, as in i had one that ended July 15th, and i didn't have another till September 5th. At that point i thought i was having a miscarriage because of the horrific pain and clotting. I had all the signs of pregnancy, down to my feet being slightly swollen. I went to the obgyn and was checked out. No baby, they did minimal tests and never confirmed if we were pregnant and lost a baby...i thought AF would begin to show up in a timely manor there after, but i was wrong. I didn't have another period after September 5th until last weekend. My obgyn hadn't done any tests seeing about fertility, or if there's an underlying problem. After struggling and fighting with him for years now, i had a previous pregnancy and lost her, i finally talked to my PCP who has set me up with a much more reputable obgyn. Until then i don't have any idea as to what's going on with my body. Has any body else experienced this? Missing multiple periods and having extreme pain when they finally arrive?