What is wrong with my house?

My house was built in the 60s. Small ranch on a slab. Both my husband and I have autoimmune diseases. All my animals have had some type of illness including 2 cats I have now. Constant vomiting—the vet said that on paper they are healthy-nothing in the bloodwork shows anything wrong. Can there be something ‘invisible’ in my house that could be causing our illnesses? It seems so bizaar that two people from different background and nationalities, both develope auto-immune diseases. Can anyone offer some insight to this?