Brief Answer:
It can be cold sores or HFM disease

Detailed Answer:
Hello

Thanks for asking on this platform

I can understand your concern.
Although high grade fever is an important characteristic of Hand Foot Mouth disease,sometimes fever may be mild or remain unnoticed.
The other common cause of swollen gums,blisters in mouth and on face can be due to cold sores(Herpes simplex infection).
As the baby does not has associated high grade temperature the chances of severe bacterial infection or other diseases like Kawasaki disease is highly unlikely.
I won't get overly worried as both these condition(HFMD and Cold sores)are self limiting and don't need any specific treatment.Only conservative treatment like local application of ointment,multivitamin,good hydration is sufficient.
I request you to attach an image,so that I better able to assess the condition and help you out.

Please let me know if you have any more query.
Wishing for your baby's speedy recovery.
Regards

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Brief Answer:
Blister can be there on face in HFMD/Cold sores

Detailed Answer:
Blister can be there around the oral cavity in HFMD. It can also be there in Herpes infection.
Bad breath is a very common association in both these condition due to poor hygiene.
Cleaning of tongue and rinsing mouth with Chlorhexidine relieves the bad breath.

Regards

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