Made the mistake of looking after my friend's cat and now I'm miserable

A month ago I agreed to look after my friend's cat while she way away for two weeks. I previously had no idea that I might be allergic to cats since I had been to her house pretty often, staying for hours at a time and played with her cat but never had any issues, or at least I never noticed.

But the very night after she had brought her cat to my house I started sneezing and getting a runny nose. At first I thought I'd gotten the flu again because I was sick the previous week but was also quite busy so I didn't really have time to recuperate. But I started suspecting they were allergy symptoms when I didn't have a fever and my eyes were itching like crazy. I took cetirizine but it barely worked even though it's usually very effective for me when I get a stuffed nose. After that I took Lorano pro which was better but my nose was still crazy congested at night.

It's been two weeks now since my friend took her cat back home but I still sneeze and have congestion every night. And because I can only breathe through my mouth, my throat is really dry as well.

I've already vacuumed and changed all my bedding. I haven't gotten around to really deep cleaning yet but honestly I am also not really sure what to do because the cat was really in every nook and cranny of the house.

I haven't been able to sleep properly for weeks now because of how bad the congestion is and it's miserable. Does anyone have any solutions?