Weird bump that has popped, need advice/help

So my girl is doing okay I just need to know what’s going on, I have a beagle she’s about 1 or 2 years old I started to notice she was limping on her leg and if u tried to pick her up like she normally enjoys she would yip.. About a day later I noticed this red bump like thing on her chest right underneath the arm pit. We left it alone and just watch within like two days it started to swell so bad that her chest was sagging on the one side where the bump was. keep in mind we can’t take her in due to the holidays. Later on that day somehow she managed to pop this bump or blister whatever it is and a lot of puss came out a ton I mean there was a puddle. The red bump went away as well as the swelling in her chest and now it’s almost like a hole kinda. We have been cleaning it at least two times a day. She’s on a previous antibiotic we had( which we consulted a vet first) and we have been keeping it wrapped to prevent further infection. Also she is no longer limping it’s been a day since the bump popped but I want to ask if anyone has any idea what it could’ve been, should I continue cleaning it and let it heal. Or should I be taking her to the vet. I think it could’ve been some type of bug bite because I noticed two puncher marks not holes on the top and bottom of the bump. Since we have been cleaning it it’s starting to heal and now it’s barely opened she’s back to herself and no more puss is coming out but should I still be worried

Hello Emz  One explanation is that your dog had a grass seed or similar foreign body under the skin, which prompted a foreign body reaction.  Often, the original foreign body is walled off by the body's inflammatory system and pushed out through the skin, usually with a certain amount of pus.  If this is what happened however,  I am struggling to understand how an antibiotic would reach any bacteria at the site because they would be walled off with the pus - or indeed, to account for antibiotics being given without an appointment. Remember, left over antibiotics should never be used, as they can lead to resistance and the drugs no longer working. I am probably missing some detail or understanding of this case so, if your vet has been advising you on it already, I do feel that they and not myself would be the people to advise you further.  It would be a reasonable move to call their emergency cover and ask them for advice if  your vets is closed.  Having advised you already, your vet will probably have a plan in their head as to whether or at what point this patient needs to be seen.

Its worth mentioning here that authorising antibiotics for a patient and case that hasn't been seen may be in breach of the UK's new prescribing laws (see an article in our blog by David Harris, New Prescribing rules for Uk Vets).   I am therefore concerned that in this case, either your vet could be in breach of prescribing rules or you may be giving antibiotics for a use other than that which was authorised by your vet.  Either scenario could be illegal - please see the blog post for details.

In light of these new rules, but also protecting these critically important drugs for our animals and for humans, we would strongly recommend that your dog is seen and assessed by a vet as soon as possible, in order that a decision on the appropriate treatment can be made.