Hello Ala Stevenson,
Thanks for posting,
From your description what you are descriping as lump on your skull is most probably due to an abscess
( still developing to a pus) and the pain from it can radiate to other areas of the head and feel like a headache or the stabbing pain
you are describing.
Just take some NSAID and perhaps antibiotics such as amoxicillin
If it becomes softer and fluctuant, it means pus has probably collected and might need drainage
. Treatment can even make the abscess to completely clear off with the need of an excition and drainage.
Other possibilities are cysts, fibromas etc.
Hope this helps