Advice on water damage in kitchen while tenants live there

[Beth Kelly]

Hi crew. My husband and I are new landlords in Chicago -- our tenants moved in on Aug 1. Shortly after they moved in, they told us about a funky smell coming from one of the kitchen cabinets. Since then, we have been trying to figure out what's causing the smell and have heard from a mold specialist that it is not mold.

Yesterday we decided to cut out the bottom of the cabinet and discovered some moisture in the subfloor under the cabinet. This is not near the sink or a window but is next to the stove -- so in theory it could have been caused by cooking spills although I don't think that's what's causing it since there is no evidence of it immediately under the stove.

So, we need to figure out where this water is coming from and determine if we need to rip out the cabinet(s) and potentially pull up the (crappy vinyl) flooring and plywood subfloor.  All with them still living there.  

My question for the group is: what type of professional should we call about this?  Since our tenants will still be living there, it needs to be done quickly and thoroughly. Should that person be a general contractor, a handyman, some other type of job description that I haven't even thought of yet??  

Bonus question -- do you think we should offer our tenants any kind of rebate on their rent if we have to tear their kitchen apart?  How have you dealt with issues of emergency repairs in a tenant's unit?

Huge thanks for any advice or words of wisdom that you can share!