It sounds like your father had a stroke. By definition a TIA does leave the person with any neurologic changes. I think he needs to be seen by a neurologist as soon as possible. Although it sounds like he had a thorough workup, I suspect that the neurologist will perform more tests than were done in the emergency room. I wonder if the MRI was truly totally normal or was it really " normal for age," With his history of high blood pressure it would be common to see many small white spots on the MRI that represent microvascular changes, or small scars in the brain. These can accumulate over time and then you can have the one that "breaks the camel's back" and causes symptoms.
The crying episodes are called emotional lability. It can be seen in people with strokes on both sides of their brain or down in the brainstem. The crying may appear for no reason at all or be triggered by what appears to be a trivial comment. It usually improves over time, but if it doesn't there are some medicines that the neurologist can try. It is impossible to predict how long the symptoms will last. Some people improve rapidly while others can be left with permanent problems.
I would make sure he gets a thorough evaluation for his stroke to make sure you are controlling all the risk factors you can and also taking appropriate medication to prevent a future stroke.
Here is a link for additional information:
Emotional Lability Good Luck
After your stroke you may be experiencing a new normal, but remember what George Eliot said- It is never too late to be what you might have been. You still can achieve new goals.