elderly miniature poodle shaking and pantng

Question
About 6 months ago, I adoped an elderly miniature poodle (12-13 years old) who had been found as a stray.  When I got her, she had subluxating patellas and 8 teeth extracted due to poor dental health.  During the first couple of months, I concluded that she had digestive problems because she had spasms at night.  Eventually I  found food that worked better and the tummy spasms went away.  A few months ago, she started waking up around 11:30 p.m. with shaking and panting.  Our vet found that she had an enlarged heart and she is now doing well on Enalapril.  However, recently, she has been again shaking and panting uncontrollably at night and I can't help her.  The vet did another x-ray and she is looking healther from that perspective, heart still large but breathing is much better and she has lost a little weight as he had recommended I have her lose about a pound.  Another uncontrollable shaking and panting episode occurred last night and lasted at least a couple of hours before going away and allowing her to sleep.  She pants really fast, doesn't want water, shakes rather rhythmically (kind of like vibration)along with the panting and moves around or walks around almost like pacing as if trying to find some way to get comfortable.  Nothing I try helps her and it appears she just has to ride it out no matter how long it takes.  I have described it all to the vet and he has no solution to the shaking and panting.  I wondered if it could be precipitated by fear like the current thunder and lightning storms we are having.  She is very sensitive to sounds like sudden sneezes or coughing.  That is, could it be a kind of anxiety reaction?  I wondered if I should get her some earmuffs or rig some sort of quieter area for her.

Answer
Hello Lin,
Sounds like your Poodle could be suffering from seizures or mild tremors.  You might ask your Vet if this is a possibility and see what he says.  Other than that, I am not really the one to speculate on this matter.  I have only limited Vet expirence.  

I hope this helps some.  
Thanks for using AllExperts.com,
Kim

My computer was hit by a storm at the beginning of the week and that is why it took so long for me to respond.  
Sorry for the delay