Pink lump / sore on roseline barb help please

[Emmzz]

Hi all I recently bought some roseline barbs about 2 weeks ago they are currently in quarantine.
In the past week one has developed a pink lump on its side near it's anal fin I'm finding it difficult to find out what is wrong with my fish I will attach pictures here the fish is eating normally.
Any advice is much appreciated as I don't know what the problem is or how to treat it properly. Hope the pics are ok was kind of hard to get a good pic.
Thanks Emma.

 

[Regent]

Any news on your barb? this is exactly what the lump on mine looked like, see here fish parasite identification