8 month old baby fell off the bed last night.?

I feel like the worst mom in the world, I can't get over it. My fiance and I put our 8 month old son in his crib to go to sleep and he has been sick lately so he just screamed and screamed like he might go crazy so I grabbed him out of the crib to comfort him, and brought him in our room. I work full time, and don't much sleep as it is... I was tired beyond words and fell asleep. Well so did the baby, but when he woke up he crawled... Off the edge of the bed. I don't know exactly what happened but he's got a bump on the side of his head and the back, I'm thinking he hit the side table and the hard linoleum floor. So I woke up to a huge BOOM and a lot of screaming and my fiance going crazy behind me. I guess at the moment he fell out of the bed my fiance was having a dream that the baby died. So the baby seemed completely and totally normal after the initial shock and screaming was over. He was smiling, laughing, moving around and didn't look out of it at all. Well we decided to take him in anyway... The dr at the ER said he looks okay. She examined him and said just keep an eye on it. He seems alright, maybe a little fussy but okay. Should I worry? I feel like such a terrible mother. I can't stand it I just wanted to cry for hours. Is it just me or does it seem like babies this age tend to bump into everything? Even if he is just sitting on the ground, he'll manage to scoot somewhere and bang his head on the wall, or on a door. I mean we watch him ALL the time. I cannot OVER protect him... I just want to make sure he's safe.