I'm unable to enlarge the thumbnail to actually view Bluebell' cere.
I agree with PoukieBear that Bluebell seems to be overweight. I also agree that when a male comes into condition, the cere becomes a much darker color blue - which you may consider a more purple color.
I suggest you take Bluebell in to an Avian Vet for a well-birdie checkup to discuss both his weight and any other concerns you may have at this time.
Avian Vets have special training to determine the cause of symptoms resulting from illness or trauma.
This is important as "regular" vets will often overlook symptoms that are quickly obvious to an Avian Vet.
When you rely on anyone who has not had training in Avian diagnosis and care, you may be delaying effective treatment.
This can prolong suffering that may be avoidable.
The bird will often require a more intense, prolonged treatment with a poorer chance of full recovery than it would have if you seek prompt professional diagnosis and treatment at the first sign of illness.
If there are no Avian Vets near you, please find an Exotic Pet Veterinarian with experience in dealing with small birds.