When i apply oil on my hair , after two days some thing like tumor shown on my rt side bottom neck.doc says its cervical effect. what's this?

It sounds more : Like swollen gland , which is normal. We have a lot of lymph glands in our body. They swell up to fight infection or reacting to something . They normally are self limiting unless the glands are infected , you will need antibiotics for that . If it get worst, tender to touch, having fever, you need to see your doctor.

Not related: Lymph nodes at the base of the skull and along the neck will react to infections or trauma of the head by getting larger. This normal immune reaction is not considered cancerous unless a biopsy proves otherwise. Applying oil to the hair is unlikely to produce this effect.