Bed Bugs

[Jak Dadi]

I have a tenant who complained to bed bug issues right after we purchased the fourplex. I talked to the seller of the property and he indicated that based on her complaints, he had the unit fumigated in October. He gave me all the backup which also stated that the pest control co. did not spot any bed bugs. She had 30 days to come back if she spotted any bugs, and she did not come back with further complaints. As soon as I got the property in November she has been calling 5-7 times a week that the bugs are back and she has bites all over the body. She is a Section 8 tenant and has been living there for 13 years.
She is 57 and apparently has liver trouble. How do I protect myself in this case? Do I go back and get the place fumigated. Last time, it cost the seller $750 to fumigate the unit. I am also concerned that if she has all those health issues, is it even safe to do this again? Your inputs would be appreciated. I read some articles and posting on BP on this