I agree, see a vet to get at the underlying cause.
The redness is probably due to licking.
Was your dog this dark red when you got her and did she clear to cream? I have a silver minipoo. She got a bee sting last year and where the swelling occurred, her hair started to grow in black which was her color as a puppy. It took several months before the hair started to grow lighter and lighter till it finally matched the rest of her silver. If what is causing the licking and irritation is also causing inflammation it may have caused the hair in that area to grow temporarily her original puppy color if she was red originally.
Babykins CGCA, TKP, ACT1, BN, CD, SCN, SIN, SBN, RN, AKC Achiever Dog,TDI (Therapy Dog International)
WCRL Rally titles: RL1, RL1X Award of Excellence, RL2, RL3
AKC CGCA=Community Canine Good Citizen, TKP=Trick Dog Performer+Novice+Intermediate+Advanced) ACT1=Agility Course Trial 1, BN=Beginner Novice Obedience, CD=Companion dog/Novice Obedience, SCN=Scent Work Container Novice, SIN=Interior Novice SBN=Buried Novice
C-Wags title -Scent Patrol Level 1, Scent Detective Level 2