He has an absces

The vet tryed to dran it but it so large and inflammed he couldnt do it, He got a shot for pain and a antibiotic shot, He has to go back next week, if its not better they will do surgery

I feel so bad, why didnt I notice this sooner, the vet said it is common, He sent him home on calvamaxa and some pain med, He seems to be resting better now, I asked if it had anyhting to do with his food, he said no, he is on a good diet, it just happens, he weighs 7.4 pds , Please pray he dont need surgery, I hope it will heal with the help of the meds. thank you all, I appreciate your help & prayer