Arm shaking, generic shaking, sneezing

Question
I bought two female hairless rats from Petsmart a few days ago, and they both seemed healthy enough, although when I got home I noticed that they both seem to sneeze a lot.  (I'm not sure if that is what it is, but it seems like they are sneezing.)

I am new to pet rats, but I've owned mice before and never noticed this 'sneezing'.  I am wondering if this is something that rats do or if they might be sick?

They also shake, sort of like a dog shaking off water, frequently.  Just for a second, and through the whole body, or just the head.  Is this normal?  

Finally, I just noticed one of my rats, when standing up, her front arms vibrate violently.

Like I said, I am new to rats and am wondering if these are normal behaviors or if I should consider going to a vet.  They both eat and drink fine, sleep all day, play all night, etc.  Besides the strange shaking, they seem to act fine.

Answer
Your rat just had a seizure.  Was she flinging her arms around like she was swatting flies, and afterwards, was she exhausted?

My website has alot of accurate information on health care, from proper diet to common and not so common ailments.  Sandyscrittercity.com   Please look over it and make sure that you focus on mycoplasmosis as this is a very  common bacteria rats are born with (non pathogenic to humans etc.and no, we cant catch it so dont worry)

As for why your rat had a seizure: how old is she first of all?  What type of litter do you use?  Is she in a cage or tank?

How often does she get out to play and where does she play?