Boy this sounds serious. You surely must resolve this to use propane.
Moments ago I just looked at the propane valve on my PC in the garage. I would get a small adjustable wrench, or better yet, the right sized box wrench, and make sure all fittings are tight, including what is hidden behind the white plastic shield. The last fitting to check is the one right behind the turn handle itself. You must have the valve wide open in order to get the wrench on that one. With all other fittings checked first, this would be the last one. Opening the valve to check that fitting, your leak might already be resolved.
Once all fittings are checked to be tight, you can safely check for leaks by pouring soap suds over all fittings. Watch for bubbles. Dish soap works good for that.
If you do this all, please report back as to your findings. Hopefully it's a very simple solution that a simple tightening with a wrench resolves. That is much easier than getting someone else involved.
