Can anyone help me with identifying odor in kitchen and under kitchen sink?

Mysterious chemical-like odor under kitchen sink which can also can be noticed (more subtly) in the kitchen overall. New home purchased 3 months ago. Did some kitchen work...installed new sink, pipes. The odor is definitely not from anything stored under cabinet. It is driving me crazy and I really want to get to the bottom of it. Wondering if it's sewer gas or some kind of mold/mildew problem from wet wood under cabinet. I'm at a loss and will do anything to resolve this. Thinking of getting an air/gas check. Also, don't know if it's related but our plumbing is a bit weak in terms of vacuum/suction. Anybody have any advice? Thanks!