Feel so gross

so a couple of days ago I saw a bed bug which explains why I've been getting bit when I sleep, so I killed it and then sprayed the bed and everything around it 3 times. My roommate called out apartment complex and let them know about it because they've had a bedbug outbreak before. The next day the inspector came and said he couldn't find anymore but that he will still have to spray and that it will be 325 dollars, so I'm out 325 dollars which is frustrating on top of I don't know where these bedbugs came from... like this mattress is new and my room stays pretty clean and I mop the floors with bleach... I just feel so gross and I can't hardly sleep now because of it. What are somethings I can do to keep them away?

*UPDATE*

Not even a week after the exterminator came the bed bugs came back... on top the apartment complex owners did not talk to the person upstairs who we are pretty sure is the one who started it. so I'm pissed and ready to move out 😡 on top of the exterminator stained our mattress and wouldn't own up to it