First, make sure you report the incident to your employer. If he/she refuses to take a signed/dated report, write one yourself and serve them with a copy by mailing it registered, signature required. Second, from what I have read about miscarriages, they can be very traumatic but also be the cause of additional health problems. I recommend you seek the help of your obgyn to get a physical exam as soon as possible. He/she can determine if you were indeed pregnant and advise you as to your next course of action, i.e., bed rest, medication, etc. And, do not wait. Our health should be our number one priority!
I will add that with all 3 of my miscarriages I had excruciating migraines and was super nauseous. It was miserable. I never had bleeding though until after my d&c's. I also had migraines and morning sickness really bad in the beginning of my current pregnancy and I'm 28 weeks now.
They should also be able to run a blood test on you to find out if you were/are pregnant. If your hcg comes back above a certain level then yes you were pregnant. And you may still be. Sometimes bleeding. Even heavy bleeding doesnt mean you miscarried although because of the fall that may be what happened but I would go get checked out just to be sure.
If u missed your period I would think that sounds like a miscarriage. Especially because of the clots. Are u having cramps at all? You may want to go see your dr and they can test it I believe if u take a sample of the blood clots.