Home Remedy for Severe Painful Pimple on Scalp

Hi Grandma,
I am 26 years old guy. I am away from home and my food style has changed. From past few months I used to find pimple like bumps on my scalp which were small. But from past few days I find that few of them are really big ones and it pains a lot. Because of this I feel one part of my head to be heavy and feel tired.
I usually keep my scalp clean. I massage with oil once/twice a week. Yes. I do have a little dandruff. I tend to have my hairs moderately long till shoulder.
Because of these problem I thought short hair cut would reduce the pain. Its been almost 2 weeks since i took haircut. One big bump was almost disappearing, one more emerged exactly at the opposite side. Again with the same pain. Surprisingly what I noticed was that, the part of the scalp where I had got the pimple earlier, has smoothed the surface with hair loss. I have attached a picture of it.
I kindly request you to help me regarding the hair loss, pain and suggest a remedy for these acne like bumps on my scalp.