Could this be a methlab?

me and my husband live in a duplex and we live up stairs on the top half. They have this place split to where the basement is cut in half and the neighbors have half and we have half. When we first moved in 3 months ago my husband noticed an overpowering smell of moth coming from the house EVERYWHERE down stairs only detectable when near there basement door, the woman was quick to tell my husband it warded of snakes in the basement. me and and my husband have NEVER seen snakes in the basement. Now we are smelling chemicals coming from the vents and when we smell it, i get sick and being 7 months pregnant this makes me nervous. Since we moved in our cat is more hyper, me and my husband more violent towards either and my dog extremly depressed. there are no urine smells just smells like old spray paint, but it never smells that way in the house and weve been smelling it everyday since we moved it. could they be doing somthing down there? we smell it even when the neighbors arent there, so i dont think they are doing any home improvement spray painting....