Welcome to the forum,
Are you saying that you have Not been using any water conditioner?? Or that you aren't sure the one you're using is working? Please be specific. I cannot stress enough that using a water treatment IS ABSOLUTELY CRITICAL! If you use untreated water, your frog will "Tox Out" and die. I use Reptisafe by ZooMed. It works great; I've never had any problems with it.
How old is the frog? How long have you had it? What size tank is he in? What light are you using? What has his diet been? Do you use vitamin supplements and Calcium dust with D3? Has he had any bowel movements lately? Are there any other symptoms (skin abrasions, lethargy, runny stool, impaction, etc)? What are the temp and humidity levels kept at? Is there anything around his environment that could be causing stress? (too much noise or visual distraction, other pets, drafts from windows or air vents have all been known to stress out pacmans; when they get too stressed they often stop eating.) These are all important questions. The more details we have the easier it is to help your frog.
Fifteen days is much too long to go without food, particularly if this is a young frog. It is best to seek veterinary help. In the mean time, you need to force feed. Take him out of the enclosure and set him on some damp paper towels (moistened with dechlorinated water). It is easier to do if you have two people: one to hold the frog steady and the other to open his mouth and insert the food. Gently cup the frog from behind to keep him from backing away. The other person uses a credit card or shopper card to pry his mouth open. (I prefer the shopper cards because they are smaller but still firm.) Insert the card on one side of the mouth (it should be about where his stripe comes down his nose). Gently but firmly press down, increase the pressure until he opens. You should have the food item ready in your other hand and pressed against his "lips" so that as soon as he opens you can stick it in his mouth. You don't have to get the entire item in his mouth. Once food is partially swallowed, their instinct will usually take over and they will swallow it the rest of the way. He will try to swat away the card and the food. It will take several tries to get the food in his mouth. It is best to use worms. Dust the worms with a vitamin supplement. I use Rep-Cal Herptivite multivitamins and Fluker's Calcium dust with D3. Both should be available at any pet store. (please note that multivitamins and calcium dust should not be used in the same feeding as the frog's body will not optimally absorb them when used consecutively). Worms are much easier to digest. Anytime an animal goes long periods without eating, their stomach shrinks, so soft smaller food items are better. Bigger items or items with shells, exoskeletons, or bones are harder to swallow and require much more energy to digest. Your frog does not have any extra energy. He needs nutrients immediately. If you can, pick up Flucker's Repta Aid. It is an emergency aid supplement that works very well. It comes with a tube syringe that you squirt the supplement into the frogs mouth.
Shedding problems are most commonly the result of improper humidity levels, however, in your case they are most likely also caused by not eating. No nutrients are going into his body so his skin becomes dry and brittle and he cannot shed properly. Please answer these questions and keep us posted.
EDIT-You must also when using the compressed brick Eco Earth or any coco fiber substrate that is in this form expand it in warm De-chlorinated water. Your frogs should never be exposed to any chemicals inclueding the oils on your hands. You must wash your hands very thoroughly with a very mild cleanser before handleing your frog.