Something at my girlfriend’s house is killing me and I can’t figure out what it is.

Hello, I’m going a bit desperate here. I’m pretty fit (34) ex-occasional smoker but quit about 3 years ago. Now I run 5k every morning, surf, swim, play badminton, never had any health issues until recently.

Since I started going out with my girlfriend about a year ago, I’ve been dealing with fatigue, headaches and shortness of breath. Occasionally, there is a day or two when I feel great and my lung capacity is normal. Since I’ve moved in with her about 4 months ago, it’s gotten worse. I can’t concentrate and have been falling asleep at work.

I never lived with cats and she has two ragdoll cats. Two blood tests and prick test showed that I’m not allergic to cats, only to mold and birch trees. There are no birch trees around but also no mold in the house. The only mold could have been in the sofa which we replaced. Once I put my head in the cat tunnel and couldn’t breathe but when I play with cats I’m fine. It’s definitely tied to her house. My IgG immunoglobulins are low 5.0. I’m going nuts, any ideas what could it be?

Thank you for any tips 🙏🏼