There are usually 3 reasons why you could have developed this problem:
1. If the nail bed had been damaged during the procedure.
2. If you had suffered any injury to the nail bed during the healing, until the new nail grows back fully.
3. If you had developed nail fungus infection to the nail bed during the time of healing.
There are multiple things you could try to improve the appearance of the nails, but first you need to have nail biopsy performed to determine if there is actual fungal infection. Nail bed reconstruction could be performed if there is no toe nail infection. If there is fungal infection, then you have options of topical antifungal meds, oral meds, laser treatment, total nail removal with nail bed reconstruction.
I hope this was helpful. Let me know if you have anymore questions.
Dr. Biren Shah