Dropping things ?

Yes, I was wondering, I have on several occations dropped things from my right hand at home. I wondered what and why, But they we were out and I dropped a bottle and it broke and then I was holding another one and i dropped it again. I recently in January have major back surgery and dropping things and not knowing when really scares me. I also have twitching in that hand too. I had the shakes before i had an accident where I got hit in the head by a truck door, could that have affected it by a hit in the head? I someone has any ideas it would really help.