Yes! I would suggest an exterminator. It sounds like you have not gotten rid of the fleas in the home.
The pet should be safe as long as he has on frontline and you apply it every 30 days. But now you need to work on the house so that YOU can stay flea free.
Keep in mind that the itching could be from flea allergies. It's common in cats. You might want to talk with the vet about using benadryl until he gets through this tough part.
Let me know if you still have questions.