First of all rule out any evidence of coexisting disorder like hypertention and hyperthyroidism . Go for serum TSH , ECG   Sertraline itself can cause anxiety in absence of clonazepam. Anyway you should take sertraline along with clonazepam 0.25 mgm BD and sos. You can be reviewed after 2 weeks. Continue to take sertraline at 75 mgm till then

For proper dose please consult with psychiatrist, I think psychiatrist would you exact dose which is needed by u. But i advise you to Consult psychologist also,bcz along with medicinal help Counselling is very much needed.Sometime with counselling may be any therapy also be given to you.