Hello XXXXXXX ,
Thanks for posting your query.
Sudden Instability while walking could be an indication of significant underlying problems like stroke(brain hemorrhage or embolism ), neurological disorders due to space occupying lesions in brain or due to inner ear disorders or rarely due to sideffects of medications .
Considering your age it is important to rule out any cerebrovascular pathology hence its advisable you consult your doctor or a urgent care facility as soon as feasible to get your blood pressure and other vital parameters checked.
If there is any change in your medication or the dose then kindly mention the details and do inform your treating physician of the same.
Meanwhile it's advisable that you avoid any strenuous activity and rest in lying down position as much as you can till further evaluation.
Please do not panic as it can turn out to be a minor inner ear ( balance) disorder too and I do not intend to say that it's definitely something serious .But nevertheless it's best to get evaluated and rule out any serious cause to be on the safer side.
So relax but do not neglect your symptoms.
Hope I have answered your query.
I'll be available for any follow up queries.
Regards

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