Just a note on monitoring blood pressure: you need to measure your BP in the same time of the day, over a period of at least 2 weeks to be able to draw useful conclusion, and make sure to take the time to quiet down before taking the measurement.
There should be a good reason that the doctor didn't prescribe medication for your father. Taking someone else's medication is very dangerous. If you don't trust that doctor, ask for a second opinion.
In my own experience, dizziness can be caused by lack of sleep, or stress or being hungry while on diet. Don't go to emergency room for soemthing like this, go to see your family doctor, and if you don't have one, just go to any walk-in clinic. Look in the yellowpages for AppleTree, they normally allow walk-in patients.
Has your father been diagnosed with hypertension before? If so, why didn't he bring his medication? If not, then his dizziness is probably not caused by high blood pressure. 90/148 is a little bit unusual, but still within normal BP boundaries, nothing to be alarmed about.