Hi..
Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concerns..
As per your complain itchy bumps over the scalp can occur due to causes like hair 
follicle infection of 
Folliculitis, bacterial infection causing Impetigo, 
allergic reaction causing 
Contact Dermatitis etc..
I would suggest you to consult a Trichologist or 
Dermatologist and get evaluated and a thorough clinical evaluation and investigations like microscopic examination of the scrapings from the scalp and blood tests can help in diagnosis and treatment can be done accordingly..
You can be advised antibiotics, anti inflammatory medicines, anti allergic medicines and topical application of antibiotic and steroid ointment..
Avoid scratching the bumps to avoid infection..
Wash the scalp every alternate day with a mild shampoo..
Avoid moisture accumulation in the scalp..
Hope this information helps..
Thanks and regards.
Dr.Honey Nandwani Arora.