I'm so sorry you're going through this yet again, particularly so soon after your D&C 7 weeks ago. I've been silently stalking this thread, and I just couldn't stay quiet any longer.
I've had 2 miscarriages in a row (within a 6 month time frame), I'm turning 34 in less than a month, and have no children yet. I hate to be the negative voice of your thread, but the reality of the situation is that bleeding in pregnancy happens, but it's rarely normal. I think we read of it happening so much online, and things turn out okay for a lot of these women, but really, in the bigger picture, bleeding is often the first sign that something is amiss. Although I'm no doctor, it sounds to me from the description of the clotty/tissue thing you passed, that you have indeed miscarried. At 4 weeks, whatever this thing was that you passed was NOT the baby, as the baby is so tiny at this point, it would be no larger than a poppy seed.
I am so sorry this is happening to you...I know how painful this situation is. Two miscarriages in a row is a tricky spot to be in, because most often, doctors won't test after 2...they want to wait to test until after you've had 3 consecutive losses. So, it's like being stuck in an impossible state of limbo.
I can tell you right now that over 90% of all early miscarriages (and chemical pregnancies/miscarriages, such as this was in your case) are a result of chromosomal abnormalities, or a lethal recessive genetic trait. This is a very common issue, and so many more women experience it than what you'd ever imagine. There are some tests that could be run now, such as a thyroid panel, and tests to see if you have some sort of blood clotting disorder, or other autoimmune issue. This can all be looked at, when you're ready, and once you've given yourself time to grieve and heal.
I can tell you right now, that consecutive losses are tough, and nothing anyone can say to you will make it better. Your DH will never understand...men don't become fathers until they SEE and HOLD their babies. Women become mothers at conception. So don't get too frustrated with him that he can't share in your grief...he'll be merely an observer, and can only try to empathize. The last thing you two need to be doing at this point is fighting, and he should not be telling you to leave the house. It's one thing to not be capable of understanding what you're going through, but it's another to act like an insensitive ass-pony.
If things start getting too tough emotionally for you (and I've been there, too), don't be afraid to reach out for help. Currently, I see a counselor, and attend a monthly support group for those who have experienced baby loss. I urge you to know your threshold for suffering, and if it feels to be too much, then it's time to see someone, or get involved with a group.
If anyone outside of BnB knew about this last pregnancy, be prepared for people to say a whole lot of stupid things. "At least you know you can get pregnant." "What's wrong with you? Obviously something is wrong..." "Everything happens for a reason." "At least you lost it early on." "At least you have two kids already."
I can tell you right now that unless these people have gone through it, they're incapable of understanding it, and most of the time, they don't know WHAT to say to help, and end up saying really insensitive things, thinking that they're actually helping. These comments used to make me hostile. Now, I see that these people say things out of ignorance, and I can't continue to walk around angry with them because of that.
It's a process. And you need to allow yourself as much time as you can to cope, to cry, to be angry, etc. Recurrent loss is a very tough journey.
Please feel free to stop in my journal, or PM me if you need to talk, or just let it out. Again, I'm so very sorry for your loss.
... Went to the toilet and something really big just slipped out, so I checked in the toilet and there was a big tissue clump, pinky looking, with lots of dark liver looking things 
