I suspect the heading of your posting is correct - separation anxiety. I might suggest you google the phrase "separation anxiety and toddlers" or "behaviors of anxiety in young children" or similar words/phrases to learn more about this issue. The age of your daughter is one in which "separation" is often an issue - it means they are growing up and realizing that they are not attached to mom and so will need to become independent - a scary thought for some toddlers.
The only thing that will change her behaviour is to lessen her anxiety (spanking and time-outs don't work but you already know this); There is lots and lots of information on the internet as well as many excellent books in your library. But, anxiety can be a lifelong issue and, if anxiety is the problem, it will not be conquered in a short while. By the way, one of our granddaughters would have "fits" that lasted for hours so I consider your 30-minutes relatively short. One other point is that many children who suffer from anxiety also have sensory issues - perhaps the reason for the discomfort in the car seat. You might also wish to google "sensory issues in children" or "sensory integration disorder" or similar words/phrases.
If it is any consolation from what you have written, it does not appear that your daughter is severe in either anxiety or sensory issues but might need some "help" from parents who understand and "know" how to soften her environment re anxiety and sensory. I wish you the best ....
thx for the thoughts. it's funny, my wife and i were talking about how big sister is so sweet to little one and gets nothing but the downside of the little sister... big sis gets to hear her yell, fit, scream, doesnt get to go to restaurants, etc bc little sis is so poorly behaved.
we're definitely trying to ignore the behavior and can do that when in private but when on vacation or out/about, she can be such a distraction to other people that we don't want to impose on them... and a recen plane ride was an all-time low in little sis' behavior.
i agree, we're likely to wait it out. pediatrician said she's doing great from mental and physical development and hinted that these were "terrible two's just a bit early" which is likely but very heartbreaking nonetheless while we're in the midst of the phase.
thx so much for the reply.
What happens prior to her having the 'fits' what would you think triggers them , usually there is something, is the 4year old sibling kind to her, no jealousy going on ? When you put her into the seat do it quietly and firmly if you yell back or say too much you are feeding the frenzy ,stay calm, and once she is in the seat leave her to yell, switch off , if shes getting no attention she may decide its not worth while .It is good you dont use any spanking on her and time outs will work better as she gets older. At this age ignoring a lot of it may work better as sometimes the more you make of a tantrum the more it becomes.good luck its tough but very common ....