what you have is alopecia areata
and inj kenalog is a steroid
one.its effect last minimum 30 day.
it will take around 5-6 month to recover ur problem.
but if you plan to pregnancy
better to not go for injection.
just apply topical lotion-topisal night time.
you can consult ur dermetologist for more option.
you can leave it as it is.it may recover its own,but it will take time..
dr gaurav patel,ahmedabad