Hello,
You can take him to the emergency clinic to have this examined and treated. Though it does sound like it may be a piece of glass or a bee sting. It would be better if you could check the paw over yourself to see what it is. Though if he will not let you anywhere near it then it likely needs to be looked at to make sure it was not a snake bite.
Allowing him to try and lick on it may not be a good idea either. If it is glass he can cut his tongue trying to get it out. A large gash on the tongue is very hard to treat and should it become infected this could cause him to lose the tongue.
If you can put a muzzle on him and have someone hold him down you can examine the paw and remove what is causing the problem.
Walter
Breeder
Breeder and pet health consultant. Have spent a number of years with Behavior Training &health care.
A emergency vet visit is high, and I understand your concern so waiting till tomorrow is fine. Though I would suggest putting a sock over the foot and taping it on to keep him from licking. The problem is even a small piece of glass can cause a nasty cut on the tongue. The tongue is not like skin, it is not tough and with glass it can cut into the tongue very deeply.
You can try to flush the object out with water. As for Peroxide, it can be used on your dog. It is not poisonous for dogs to use this. In fact Peroxide is commonly used to cause dogs to vomit up poisons.
Once you rinse it with peroxide only small amounts will stay on the paw. There would not be enough to make him sick.