Damage on the frog's skin when you first get it is probably due to being banged around while in transit. However, if the injury doesn't heal in a few days the damage could be the result of a bacterial infection. If it doesn't heal over the course of a week or so, the frog needs to be taken care of by a vet.  If not treated, these infections and wounds can let harmful bacteria into your frog's body. This can result in death. Sores and bruises, as well as cuts, can cause a frog's skin to look strange. If your frog's eyes are smoky, cloudy, foggy, or blueish, it most likely has a condition known as Cloudy Eye. This occurs when the eye is bashed, poked, or scratched. If your frog's eyes are cloudy, you should get it veterinary care. If your frog has lost weight, it may have either an internal parasite or Metabolic Bone Disease (MBD). A vet can cure both MBD and a parasitic infection, so take your frog to be seen by a vet if it has lost weight. If your frog has gained weight, this is probably due to overfeeding, or it could be a sign of edema. Cut back on the amount of food it gets and make sure its weight stabilizes by weighing it every few days.  If your frog is losing weight, it could be that your frog is just naturally thin or that it needs to be fed more. You will need a digital scale to weigh your tree frog. Set a container with a lid on it on your scale and zero it out. Then put the frog in the container and read the screen. If you plan on documenting the frog's weight over time, be sure to write down its weight every time you weigh it.
Look for sores, cuts, and bruises. Inspect your frog's eyes. Monitor your tree frog's weight.