Your landlord responded to your complaint by performing an extermination. You didn't say whether the extermination was successful, but I assume that this is the case or you would have mentioned it.
I understand your fear, but your landlord has done what is required of him under Pennsylvania law. Unless your symptoms have returned, I suggest that you look for a new place when the lease expires and give proper notice. Check your lease to see if there is any provision that would enable you to leave early. You may find that you can do so with proper notice and payment. But make sure you have somewhere to move before you give notice.
Clifford L Tuttle, Jr
Attorney at Law
The foregoing answer does not constitute legal advice and does not create a lawyer-client relationship. Answers are based upon the facts stated and may change if there are additional facts not contained in the question.