Take him back to the vet and make sure they give you an e-collar this time and possibly a topical spray to help the foot heal. Since he was just there, they shouldn't charge you for an exam, just the actual products, which shouldn't be expensive.
Even if they fixed the paw, his licking at it can cause the problem all over again. They probably took the dressing off so soon because they didn't want the wound to be sitting in moisture -- it will heal better if left . But dogs get in the habit of licking because it makes the wound feel better temporarily, and you have to be able to break the habit by preventing him from getting to the paw so that it can heal.
Just wondering, did they say the dog had an abcess? I'm assuming that's what you mean by "removing the infection," especially if he had to be anesthetized for the procedure. If so, they should have given you antibiotics, but if they didn't, make sure you do get some.