Is it normal for dementia patients to have problems putting together sentences and have meltdowns about little stuff?

I can to add to the good advice you have already received. Speculating on a person's condition is pretty fruitless when we have no details and even then it is something for medical professionals to evaluate. Our good thoughts go with you.

Ah. If only I had had Barb's sensible precautionary view and looked at your profile first.

The symptoms you describe take on an entirely different complexion when they relate to a lady who has already had two brain surgeries. All the same, everything would depend on what the surgeries were for, and how complete her earlier recoveries were. Your wife can't be a stranger to her doctors: get her seen as soon as you can. If she's frightened, persuade her that it is sensible to have a regular review in any case (which it is).

And please take your wife's full name out of your profile.

Agree with not making an assumption that this is dementia. Make a full catalog of your observations and get her to a doctor. I would start with a neurologist.

On the FB page you started ( you shouldn't put so much personal information in your profile), you seem to refer to others who seem to be 
" interfering " in her care. Are these her parents? I have a daughter who is your wife's age and if she were displaying the symptoms you describe and her husband had decided it was dementia, i would be " interfering" in her care, too.

Your first thought is dementia? Dementia in a 38 year old would be extremely unusual. But not impossible; and besides it could be all sorts of other things. Persuade your wife to get herself checked out. If she won't, keep an accurate journal of her concerning behaviours, take it to your own doctor, and get help with getting her seen and referred.

Maybe it is something other than dementia. Find a neurologist that specializes in dementia. Yes, she could have a variety of it that is treatable.

Dear Gene,

Its obvious that you care and love your wife very much. Please take her to the doctor. She needs to be evaluated. Its very had to say what could be causing this change in her personality. If you find her doctor is not being helpful, then please seek out a second and third opinion. I hope you can find the answers you are looking for. Take care.