2 year old in pain! Please help!

[Jody32]

My daughter’s 2 year molars have erupted around a month ago but for the past 2 days she has had a fever and been in a lot of pain with her bottom right second molar. I have taken a picture and any advice would be gratefully received. Due to her age, she won’t let anybody look in her mouth but me. Thank you in advance.

 

[MattKW]

Is it just there on the one side? The rest of her gums also look inflamed, and the corner of her mouth looks nasty. Possible primary herpetic gingivostomatitis starting up.