There is insulation in the garage ceiling (below the second floor of the house) so a fiber optic camera will not work. There is leak and it does need to be repaired, you will have to cut (not rip) the drywall out because the insulation is water (or crap) logged and it will have to be removed and replaced. Use a simple $5 drywall hand saw and cut a square out of the garage ceiling around the leak, remove the insulation and this will expose the plumbing beneath the toliet and then you can make a decision to call a plumber or not. Cutting drywall is like cutting a cake with a little muscle, cut straight lines, ceiling joists will be every 16″, and remove the drywall inside the cuts. It is not that big of a deal and once you get started you will see how simple it is. You can buy a 1/2 sheet of drywall and drywall compound at Osh for less than $15 and a bag of insulation for $20.00 for replacement. Never under estimate mold, I lived in Valencia (dryer than San Diego) and I was shocked at what I ran into. Any material soaked by a leak under a toliet should be replaced anyway.