About a week ago I started getting these small red bumps on my upper arms, my left arm is worse than my right, although both arms get very itchy. I don't know what they are and everytime I scratch them they hurt and seem to get worse. Any ideas of what it could be?

To me, this either sounds like a rash or blocked hair follicles (I can't tell without seeing). Try a rash cream from the chemist, show them and see what they think perhaps. If they are blocked hair follicles, then one of those bath scrunchie sponge things and a light scrub(cream stuff with little beads) every couple of days