Less hair in one portion on baby's head.

My daughter who is 4.5 months old now,had visibly very less hair in one big potion on her head. That area also had a lighter pink shade. We shaved her head when she was around 40 days old, and it was evident on her scalp that this particular portion looked different. It had hair follicles with a pinkish colour, unlike the rest of the area which had a grey shade. Now there is some hair ( but very very less/ looks like there is no hair from a distance/ hair is a lot thinner here) that has grown, while the rest of the area has very thick hair already. Had consulted many paediatricians and dermatologist, but no doctor knew why this is happening.Her hair looks a lot better from how it was earlier though, but still it is something that is worrying us. Please help. You can see many hair follicles with hair in it that has not started growing yet. Will it grow? Is there anything we could do to help her hair grow better. Will shaving once again help thicker hair grow? Please help. Thanks.