Almost always, what you are describing is an abscessed tooth. It is painful and has been painful for quite some time, but our pets do not show us pain though they feel it. Your dog needs to have a dental with dental xrays. Be sure your veterinarian has dental xray capabilities. It is unlikely the emergency clinic has these capabilities, so you shouldn't need to go there. Antibiotics do not fix the problem alone.
It is known that one problem tooth can get an abscess and it spreads to other teeth under the gumline and you can't see it. Get the problem tooth (teeth) remove before others are affected. It is much better off without a tooth rather than have a painful tooth. Xrays are the only way to know which are affected. Often with these multirooted teeth one root is affected and can create the abscess and the other roots are not as sick, so when removing, can break and leave root tips ( ie nerves) in the mouth and be a continuing source of pain -- so be sure your veterinarian can do a gingival flap to remove all root of the bad tooth (teeth). The last step in that process smooths the jaw bone that held the tooth so that the jaw is non painful with biting down later on hard food and the pet can eat normally without discomfort.
Pets with good dental health live an average of 2 years longer Quality life - so ensure your 7 month old gets dental care at least by the age of 3 if no sooner. It's the best way to keep a long healthy life in dogs!
Pain meds, nerve blocks, and antibiotics should be used during the procedure provided the vet you choose has dental xray capability.
All pets that have had this care, their owners tell me that they can't beleive how much more puppy like she is!
There are other possiblities in the mouth, but this is most likely and this is needed to look at what is happening and the veterinarian can see if there's a different reason for this issue (unlikely).
There are a lot of good articles on this topic and what pets feel at www.toothvet.ca
Dental myths and dental truths are some good reads.