I am guessing that your BP medication is not enough for you and instead of 20 MG should start on 40 mg but before that you need to monitor your blood pressure for at least 1 week. If it is high even after taking medicine then definitely you need to increase the doses of your medicine or change medicine. Along with this if you still feel there is vertigo and giddiness then you will have to start with some other medications as well.
Next Steps
monitor blood pressure for 3 days if it is on highest side daily then increase from 20 MG to 40 mg.
Health Tips
do a brisk exercise daily and drink lots of water.