Answers

Just behind the valve handle there is a "packing nut" that sucures the shut off valve into the body of the unit. Take a cresent wrench and tighten up that nut and this should stop that leak. No need to pay for a plumber.

I think there is a plumbing problem. I would suggest you to take help from plumber. You can call them and they will see if there is any problem. I hire commercial plumbing service NJ experts to solve plumbing problems. You can also look for a plumbing expert in your area and solve this issue.