Infected fingers on the left side of the nail? Best Answer Awarded?

ive always been getting a infected finger, its the skin on the left side of the nail, they get very very sore, then they go green, till the point its very swollen, if i leave it, it will turn black, and then the skin will fall off, iff i pop it it will go away, i don't want to be bursting my skin every month, oh yes it happens every month. Im on antibioctis from my illness still nothing, even with them 5 days in my system they still come, i use tea tree oil and bath it, but doesnt always work, i started with 1 last week, now have 4! and it happends and any random time, and its not from cutting my nails, and its been happening for the last year